Nature lovers will get a rare chance to visit a usually off-limits wildlife haven in the Thames later this month as part of a festival celebrating the river.

Isleworth Ait, a large island opposite Heron's Place and the London Apprentice pub, is a sanctuary for birds including treecreepers and kingfishers and rare animals like the German hairy snail.

Access is usually extremely limited to protect wildlife but to mark World Rivers Day on Sunday, September 28, London Wildlife Trust (LWT) is organising guided tours for a lucky few.

Three hour-long tours will depart by boat between 2pm and 2.40pm. Numbers are strictly limited and places must be booked, at a cost of £4 per person, through the LWT.

The tours are part of TideFest, a one-day event heralding the ecology of the capital's watery spine and its importance to Londoners.

Also taking place on the day will be free paddle boarding and kayaking lessons, plus a fishing competition and river dipping, downstream at Kew Bridge, in Brentford.

To the south, a heritage walk will explore the River Wandle, a tributary of the Thames where there will also be fishing lessons for 12-18 year olds.

The rare German hairy snail, which can be found on Isleworth Ait, in the Thames (photo by Katie Bermingham)

Carlo Laurenzi, chief executive of LWT, which is teaming up with the Angling Trust and the RSPB to organise TideFest, said: "The Thames is an essential part of London, a vital natural resource which benefits much of London's wildlife and brings huge pleasure to Londoners and the many tourists who visit our city each year."

The Thames was so badly polluted in 1957 it was declared biologically dead, but it is now home to more than 120 species of fish, and seals and porpoises have been spotted in the heart of London.

* A full programme of TideFest events on September 28, including information on how to book tours of Isleworth Ait, is available at www.wildlondon.org.uk