Tonight I went to a fundraising dinner in support of the Garden Bridge.   I was, and remain, in support of it, in spite of the protesters picketing outside.   Joanna Lumley spoke of her original dream of an English garden in the hills of Malaysia.   Thomas Heatherwick spoke of the importance of joining the two sides of the river by having somewhere to linger as one crosses it.   I know there are lots of people who oppose it, who think that it is a folly.   But there is something attractively mad about planting an English garden in the middle of the Thames.