Chapel of St Thomas

I love this little building which stands by the side of the A4 (in fact I think that some years ago it was in the middle of the A4)
I love the fact that it has had so many uses over the years. It is all of 40 x 20 ft on the outside and I would think that the walls must be 1 ft thick. I don't know what sort of concerts they have on a Sunday afternoon but there can't be much room to swing a cat.
Will it last another 700 years?