First flight in England

I found this monument erected on 1784 in a field north of London.

'Let posterity know, and knowing be astonished, that on the 15th day of September 1784 Vincent Lunardi of Lucca in Tuscany, the first aerial traveller in Britain, mounting from the artillery ground in London and traversing the regions of the air for two hours and fifteen minutes, in this spot revisited the earth."