"it had enough alcohol in it to almost put me under the table" - would an ale usually do this to you? If not it may be the key to your problem as most ales will not be that strong. Do you know if it was *actually* strong or if it just tasted strong? If you can remember the percentage (and it is a high percentage) your search will be significantly reduced!

The next question is was it served on tap or from the bottle? If from the bottle it may well be an Innis & Gunn (I'm pretty sure they only do it from the bottle - I've never seen it on tap anyway). It would also seem to match the rest of your description.

It may well be worth giving the restaurant a ring; places usually have a few regular beers and a limited amount of guest beers. Finally if anyone has a copy of the good beer guide they may be able to have a glance (if the Whisky Museum has an entry) and this will tell you which beers they usually have on.. but won't help if it was a guest beer.