SuperTable and related entries
Unfortunately, you can't use Craft's built in relations service for reverse relations lookup with Super Table. This is because there's actually a special case for nested relations, such as a Matrix field. Craft's own relations service has special handling for Matrix fields, which we also need to make use of.

Fortunately, Josh Angell (the star that he is) has submitted a fix for this, without having to hack the core. You'll just need to alter your code to use the following:

{% set reverseRelatedElements = craft.supertable.getRelatedElements({
  relatedTo: {
    targetElement: entry,
    field: 'specialisms.linkToPage'
  },
  section: 'barristers'
}) %}

{% for relatedEntry in reverseRelatedElements %}
  {{ relatedEntry.title }}
{% endfor %}