Reporter Alex Rucki took to the Thames on Monday, January 30, with campaigners who support the Thames Tunnel as a way of preventing the regular discharges of raw sewage into the river:

"It's a freezing cold London day and the River Thames is the same grey murky colour of the sky. I step onto riverboat the Inceptor with ocean-rower Roz Savage, and it sets off in the direction of the combined sewer overflow (CSO) located under Putney Bridge, one of the 36 sewers which spill a ton of rubbish into the water when rainfall reaches as little as 2mm.

We are also joined by river charity Thames 21, and the Thames Anglers Conservancy Society who are all desperate for the construction of the Thames Tunnel.

Our boat stops and Ms Savage gets down into a yellow rowing boat in order to get a closer look at the sewage coming out of the CSO. Rather her than me.

From a distance I can see plastic bags, leaves and dirt clinging to the grates of the sewer.

The tide is low and Ms Savage boldly steps out of her boat and gets under the bridge, wading across the putrid build-up of dirt clinging to Putney embankment.

This is just a day's publicity event for Ms Savage, but Chas Newen, owner of Chas Newens Marine Boat Hire Limited, says he has to deal with the filth every day.

His company is the last marine boat hire in Wandsworth, and he has no choice but to get on with it when the sewage is particularly bad.

He said: "I am working in it - it has been getting worse for the past 10 years. We always have to scrub down afterwards and it is not very nice if it gets on your clothes."

Back on dry land I'm feeling rather queasy, just looking at the sewage seems to have had an effect."