Possible Clues:

• There's little land in the river, yet there's nothing in it
• English trifle upset, arriving at this unusual island
• Small island? Sounds like a number
• Island in Hackney, otherwise in Chiswick
• Feature of river at Chiswick had to be broadcast
• Endlessly played up in small island
• English play around island
• Small inland island
• Little lake island
• A small island in a river