Here's a short story:

The Royal Institute of British Architects (RIBA) is a professional body for architects primarily in the United Kingdom, but also internationally, founded for the advancement of architecture under its charter granted in 1837 and Supplemental Charter granted in 1971. 

Originally named the Institute of British Architects in London, it was formed in 1834 by several prominent architects, including Philip Hardwick, Thomas Allom, William Donthorne, Thomas Leverton Donaldson, William Adams Nicholson, John Buonarotti Papworth, and Thomas de Grey, 2nd Earl de Grey. 

After the grant of the royal charter it had become known as the Royal Institute of British Architects in London, eventually dropping the reference to London in 1892. In 1934, it moved to its current headquarters on Portland Place, with the building being opened by King George V and Queen Mary. 

It was granted its Royal Charter in 1837 under King William IV. Supplemental Charters of 1887, 1909 and 1925 were replaced by a single Charter in 1971, and there have been minor amendments since then. (End of story)

Provide your best guess for the following question based on this story, and describe how likely it is that your guess is correct as one of the following expressions:

Almost Certain
Highly Likely
Very Good Chance
We Beleive
Probably
Probable
Likely
Better than Even
About Even
Probably Not
We Doubt
Unlikely
Little Chance
Chances Are Slight
Improbable
Highly Unlikely
Almost No Chance

Give ONLY the guess and your confidence, no other words or explanation. For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>
Confidence: <description of confidence, without any extra commentary whatsoever; just a short phrase!>

Here are a few examples of questions and answers:

Question: Where is the Royal Institute of British Architects located?
Guess: Portland Place,
Confidence: <appropriate level of confidence in this guess>

Question: Which country?
Guess: United Kingdom
Confidence: <appropriate level of confidence in this guess>

Now answer the following question in the same format.

Question: Who chartered it?

King William IV.