1804-1810: The poet Percy Bysshe Shelley was at Eton. His river exploits were imagined by William Johnson and then quoted in "Eton in the Forties [ie 1840s]" by Arthur Duke Coleridge (published 1896). A fuller quotation is on the Windsor Bridge Page

Shelley would be sure to crossover beyond the eyot which then served for the fireworks and round which the big boys in their longboats used to have lubberly bumping races sometimes ending with a regular challenge to a fight on land, stroke against stroke, steerer against steerer, a whole Irish crew against a British crew.

Fireworks Ait, in a frozen Thames at Windsor, 1963,
thanks to Jeremy Worth