With no mortgage etc. (we've already paid for our retirement place) then I think we could live very comfortably on £41K per annum although I do intend to do some calculations to determine our average living costs once stuff stabilises at the new house.
When I last retired it didn't really last long enough to work out what income we needed, however we did spend a couple of months travelling around Europe in our motorhome and all told we averaged £79.08 per day on that trip, which equates to a little under £29K per year. More than a quarter of that was fuel costs (as we did well over 5000 miles of driving in that period), 20% was site costs, 33% was food & drink and the rest was stuff like ferries, public transport, entry fees for attractions etc. I know it's not directly comparable however if nothing else it indicates that we could shut up our houses and go full-time travelling on under £30K per annum (and on a longer term trip with lower average daily mileages and more use of free camping locations etc. I reckoned we'd easily have lived well on £50 per day, which is well under £20K per annum).