Hi, thank you for the response. First of all, it 'was' the 1st Battalion that was present at Waterloo, but there was not a Captain Williamson's Company - that does not mean he was not serving at Waterloo.
Also, I have double-checked the "MINT" Roll, this was the Royal Mint, where all the regiments sent the names of the men who were entitled to the Waterloo Medal ........ he is not included on the roll, so his next of kin did not receive a Waterloo Medal, or was there one issued.
As you said - he could have been mistakenly left off the list...........he certainly would not be the first.
There are so many mistakes on the Waterloo Roll, in fact, that is the main reason I started my Roll. In the twenty years since I have been collecting data, I have added 2350 names of men that should be included on the Waterloo Roll and were entitled to the Waterloo Medal. So you can rest assured that your 'David Bruce' should be added to that list.