Using select list with Views exposed filter when it is a custom schema through hook_views_data I need to build a page in Panels that is composed of Views displays. The page that this will make will function as a kind of workstation for a staff member displaying bespoke information about readership details, demographics, products chosen etc. etc. 

The problem is that I've inherited this project and the previous developer was hard-coding things, avoiding the Drupal API and trying to create his own CMS to handle this complex readership-type subscription system. I now have to make this something that will play nicely with Drupal rather than starting again due to time constraints.

I've used hook_views_data to expose his custom tables but because it seems to be data unmanaged by Drupal (i.e. he used nothing like nodes/ entities etc.) I don't think I'm able to exploit the node/custom field/select (https://drupal.org/node/391528) workaround I'm not sure of what I should start looking at.

Please do offer suggestions (possibly even on the wider context if it's relevant)
Unfortunately for me the project is too far gone to create the underlying design with entities, which seems to be the only way that I'm going to achieve that, so instead I am going to be using AJAX like forms which hopefully (in time) will output into Views (to save time and hopefully provide some flexibility). So for now I'm building Panels with blocks that I'm creating programmatically and then using drupal_get_form('mymodule_mainform') to add the content of those blocks with forms designed in different functions in my modules.
For that I'm using the Example module's 'block_example' module (block_example.module code pasted at the bottom here - find and replace 'block_example' with your module name if you want to paste it straight into your own .module file, remember though that you can't duplicate hooks, so copy the contents into any pre-existing functions or hooks with the same name).
To help out other people I've included the links that helped me here (may you have better luck!) &quot;joshaust.in&quot;'s .pdf was a brilliant explanation...
For conceptual understanding: http://joshaust.in/wp-content/uploads/2012/06/Entities-and-Bundles-in-Drupal-7.pdf
http://joshaust.in/2012/06/entities-and-bundles-in-drupal-7/
For attaching fields to your entity programmatically:
How to attach a field to an entity programmatically?
For programmatically creating your entities: http://www.phase2technology.com/blog/programmatically-creating-entities/
http://www.trellon.com/content/blog/creating-own-entities-entity-api
block_example.module
/**
 * Implements hook_menu().
 *
 * Provides a default page to explain what this module does.
 */
function block_example_menu() {
  $items['examples/block_example'] = array(
    'page callback' =&gt; 'block_example_page',
    'access callback' =&gt; TRUE,
    'title' =&gt; 'Block Example',
  );
  return $items;
}

/**
 * Simple page function to explain what the block example is about.
 */
function block_example_page() {
  $page = array(
    '#type' =&gt; 'markup',
    '#markup' =&gt; t('The Block Example provides two sample blocks which demonstrate the various block APIs. 
            To experiment with the blocks, enable and configure them on &lt;a href=&quot;@url&quot;&gt;the block admin page&lt;/a&gt;.', array('@url' =&gt; url('admin/structure/block'))),
  );
  return $page;
}
/**
 * Implements hook_block_info().
 *
 * This hook declares what blocks are provided by the module.
 */
function block_example_block_info() {
  // This hook returns an array, each component of which is an array of block
  // information. The array keys are the 'delta' values used in other block
  // hooks.

  // The required block information is a block description, which is shown
  // to the site administrator in the list of possible blocks. You can also
  // provide initial settings for block weight, status, etc.

  // Many options are defined in hook_block_info():
  $blocks['example_configurable_text'] = array(
    // info: The name of the block.
    'info' =&gt; t('Example: configurable text string'),
    // Block caching options (per role, per user, etc.)
    'cache' =&gt; DRUPAL_CACHE_PER_ROLE, // default
  );

  // This sample shows how to provide default settings. In this case we'll
  // enable the block in the first sidebar and make it visible only on
  // 'node/*' pages. See the hook_block_info() documentation for these.
  $blocks['example_empty'] = array(
    'info' =&gt; t('Example: empty block'),
    'status' =&gt; TRUE,
    'region' =&gt; 'sidebar_first',  // Not usually provided.
    'visibility' =&gt; BLOCK_VISIBILITY_LISTED,  // Not usually provided.
    'pages' =&gt; 'node/*', // Not usually provided here.
  );

  $blocks['example_uppercase'] = array(
    // info: The name of the block.
    'info' =&gt; t('Example: uppercase this please'),
    'status' =&gt; TRUE,
    'region' =&gt; 'sidebar_first',  // Not usually provided.
  );

  return $blocks;
}

/**
 * Implements hook_block_configure().
 *
 * This hook declares configuration options for blocks provided by this module.
 */
function block_example_block_configure($delta = '') {
  // The $delta parameter tells us which block is being configured.
  // In this example, we'll allow the administrator to customize
  // the text of the 'configurable text string' block defined in this module.

  $form = array();
  if ($delta == 'example_configurable_text') {
    // All we need to provide is the specific configuration options for our
    // block. Drupal will take care of the standard block configuration options
    // (block title, page visibility, etc.) and the save button.
    $form['block_example_string'] = array(
      '#type' =&gt; 'textfield',
      '#title' =&gt; t('Block contents'),
      '#size' =&gt; 60,
      '#description' =&gt; t('This text will appear in the example block.'),
      '#default_value' =&gt; variable_get('block_example_string',  t('Some example content.')),
    );
  }
  return $form;
}

/**
 * Implements hook_block_save().
 *
 * This hook declares how the configured options for a block
 * provided by this module are saved.
 */
function block_example_block_save($delta = '', $edit = array()) {
  // We need to save settings from the configuration form.
  // We need to check $delta to make sure we are saving the right block.
  if ($delta == 'example_configurable_text') {
    // Have Drupal save the string to the database.
    variable_set('block_example_string', $edit['block_example_string']);
  }
  return;
}

/**
 * Implements hook_block_view().
 *
 * This hook generates the contents of the blocks themselves.
 */
function block_example_block_view($delta = '') {
  //The $delta parameter tells us which block is being requested.
  switch ($delta) {
    case 'example_configurable_text':
      // The subject is displayed at the top of the block. Note that it
      // should be passed through t() for translation. The title configured
      // for the block using Drupal UI supercedes this one.
      $block['subject'] = t('Title of first block (example_configurable_text)');
      // The content of the block is typically generated by calling a custom
      // function.
      $block['content'] = block_example_contents($delta);
      break;
    case 'example_empty':
      $block['subject'] = t('Title of second block (example_empty)');
      $block['content'] = block_example_contents($delta);
      break;
    case 'example_uppercase':
      $block['subject'] = t(&quot;uppercase this please&quot;);
      $block['content'] = t(&quot;This block's title will be changed to uppercase. Any other block with 'uppercase' in the subject or title will also be altered. If you change this block's title through the UI to omit the word 'uppercase', it will still be altered to uppercase as the subject key has not been changed.&quot;);
      break;
  }
  return $block;
}

/**
 * A module-defined block content function.
 */
function block_example_contents($which_block) {
  switch ($which_block) {
    case 'example_configurable_text':
      // Modules would typically perform some database queries to fetch the
      // content for their blocks. Here, we'll just use the variable set in the
      // block configuration or, if none has set, a default value.
      // Block content can be returned in two formats: renderable arrays
      // (as here) are preferred though a simple string will work as well.
      // Block content created through the UI defaults to a string.
      return array('#markup' =&gt; variable_get('block_example_string',  t('A default value. This block was created at %time', array('%time' =&gt; date('c')))));
    case 'example_empty':
      // It is possible that a block not have any content, since it is
      // probably dynamically constructed. In this case, Drupal will not display
      // the block at all. This block will not be displayed.
      return;
  }
}

/*
 * The following hooks can be used to alter blocks
 * provided by your own or other modules.
 */

/**
 * Implements hook_block_list_alter().
 *
 * This hook allows you to add, remove or modify blocks in the block list. The
 * block list contains the block definitions. This example requires
 * search module and the search block enabled
 * to see how this hook implementation works.
 *
 * You may also be interested in hook_block_info_alter(), which allows changes
 * to the behavior of blocks.
 */
function block_example_block_list_alter(&amp;$blocks) {
  // We are going to make the search block sticky on bottom of regions. For
  // this example, we will modify the block list and append the search block at
  // the end of the list, so even if the administrator configures the block to
  // be on the top of the region, it will demote to bottom again.
  foreach ($blocks as $bid =&gt; $block) {
    if (($block-&gt;module == 'search') &amp;&amp; ($block-&gt;delta == 'form')) {
      // Remove the block from the list and append to the end.
      unset($blocks[$bid]);
      $blocks[$bid] = $block;
      break;
    }
  }
}

/**
 * Implements hook_block_view_alter().
 *
 * This hook allows you to modify the output of any block in the system.
 *
 * In addition, instead of hook_block_view_alter(), which is called for all
 * blocks, you can also use hook_block_view_MODULE_DELTA_alter() to alter a
 * specific block. To change only our block using
 * hook_block_view_MODULE_DELTA_alter, we would use the function:
 * block_example_block_view_block_example_example_configurable_text_alter()
 *
 * We are going to uppercase the subject (the title of the block as shown to the
 * user) of any block if the string &quot;uppercase&quot; appears in the block title or
 * subject. Default block titles are set programmatically in the subject key;
 * titles created through the UI are saved in the title key. This module creates
 * an example block to demonstrate this effect (default title set
 * programmatically as subject).  You can also demonstrate the effect of this
 * hook by creating a new block whose title has the string 'uppercase' in it
 * (set as title through the UI).
 */
function block_example_block_view_alter(&amp;$data, $block) {
  // We'll search for the string 'uppercase'.
  if ((!empty($block-&gt;title) &amp;&amp; stristr($block-&gt;title, 'uppercase')) || (!empty($data['subject']) &amp;&amp; stristr($data['subject'], 'uppercase'))) {
    // This will uppercase the default title.
    $data['subject'] = isset($data['subject']) ? drupal_strtoupper($data['subject']) : '';
    // This will uppercase a title set in the UI.
    $block-&gt;title = isset($block-&gt;title) ? drupal_strtoupper($block-&gt;title) : '';
  }
}