Is it a bird? Is it a plane?

This came as a complete surprise, I'd been taking photographs around the River Adur just west of Hove and wandered down to Shoreham to check out the houseboats. It was low tide and I thought maybe there would be a nice shot in there somewhere. This stretch of the river is very 'alternative' - tattoo parlours, yoga retreats, and living sculptures - somebody I chatted to said the council enforce their community charge on these dwellings...