Slightly OT, but the Saturday before last I had a pint of Cairngorm Tradewinds (3.8%) in the Boat Country Hotel across the road from Boat of Garten station on the Strathspey Railway. Because it was table service only (and card payment only) the price was not immediately apparent, but I was somewhat shocked when my bill arrived to find that it was £5.60! An hour later, I walked into the Winking Owl in Aviemore - which stocks a range of four different Cairngorm ales - and was pleasantly surprised to find that my pint of Wildcat, their 5.1 % strong red ale, cost a mere £4.20.
For anyone who has time to spare at Kings Cross or St Pancras - and like me is not a fan of Wetherspoons - I can recommend the King Charles I in Northdown Street, Pentonville, which is less than ten minutes walk away. This is a relaxed, friendly co-operative pub, owned by the local community, where on my last visit in January all three of the ales available cost £4.20 a pint, regardless of strength. They don't do food, but you can order a meal from the cafe across the road and they will bring it across to the pub for you.