River Thames shipping coming in and out of London, in 1732 it received the world's first lightship. This became a major landmark, and was used as an assembly point for shipping. Today it is marked by Sea Reach No. 1 Buoy. The River Thames contains over 80 islands ranging from the large estuarial marshlands of the Isle of Sheppey and Canvey Island to small tree-covered islets like Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. They are found all the way from the Isle of Sheppey in Kent to Fiddler's Island in Oxfordshire. Some of the largest inland islands, for example
Canvey Island the present island, with a ditch being the current boundary, having the same far eastern points as the Canvey Point and Leighbeck Point marshes. Two Tree Island to the north is also recognisable, if halved in length. The third eastern island or mudflat could well be the Counus i.e. "council" Island where the Trinovantes, Cantiaci and the Catuvellauni counselled with the Iceni, shortly before staging Boudicca's rebellion against the Romans. If so Counus occupies an area from the Canvey Point Sand Bank until just before Shoeburyness, the eastern point of the relatively straight estuary so stretched the whole length of