Thanks all for the ideas: I do believe it's the Battle of Britain, as the dates align, but I've been unceremoniously dropped from that planning (honestly, to me one war aeroplane is as fine an another). And more the better. He's giddy with excitement - I'm looking forward to the botanical gardens, wandering around and maybe just sitting and people watching with a nice tea. Fingers crossed for good weather.
Rather dull question: there must be some tremendous bookshops. Any favourites? And places for tea that are quiet and interesting? Also, lovely restaurant recommendations for the evenings would be most welcome.