Beyond Putney Bridge the river starts to feel a little less urban.

A mosaic celebrates the Oxford – Cambridge boat race as the world’s longest running sporting event – from 1829.

Instead of vertical embankments, the south side has long concreted slopes. Houses start to have gardens that run towards the river.

On the north side the tow path is overshadowed by huge plane trees, reaching overhead and dipping their branches into the river as though they are drinking it.

Opposite the wetlands on the Barnes peninsular, a gulp of cormorants sits waiting on a jetty, some with their heads up hoping to summon the sun.

The Harrods Furniture depository by Hammersmith Bridge looms enormously with its twin domes and art nouveau lettering like a living fossil – as though you could walk into it and meet P. G. Wodehouse. It is, of course, now redeveloped into flats. None of them “affordable.” Its quite possible Wodehouse wouldn’t be able to afford one.

Rain looms in the moisture soaked west. Visibility begins to dim. We are walking towards three broad curtains of rain. If one of them doesn’t get us, the others will.

A Chinese family walk past leading a big curious dalmatian. Other pedigree dogs are walked in the park alongside.

The familiar shape of Wembley arch appears on the horizon in front of us. We are not sure whether to believe our eyes or not – because it means that we have walked all day just to end up closer to home – and far from heading directly West, at this point we were actually heading North as the river begins to meander quite wildly past Putney.

As the rain blew in we headed inland for food and landed in Hammersmith. Six and a half hours after setting off and we’ve done about 20 miles but are nowhere near Hampton Court. The map shows that we have almost as far to go again as we have covered already, so, as creatures of habit, we find ourselves in the familiar surroundings of the Hammersmith Nandos, which could be a Nandos anywhere, Playing safe on a journey of discovery, so I have something new on the menu to compensate that turns out to be extraordinarily bland; and serves me right. A tall and alienated looking family sits in the reception avoiding conversation and eye contact with each other. The son, who must be about 18 and looks determinedly grumpy, slouches back in his seat and has a Donald Trump style comb forward. “There were some gilded youths, that sat along the barbers wall. Their eyes were dim, their heads were flat. They had no brains at all.” A.B. Paterson .

Having sat down, the prospect of getting up again is not attractive. Agreeing to walk on to the next Bridge as an act of futile bravado, we have barely taken a dozen steps before I realise that my feet just aren’t up to it. This is a salutary, if slightly depressing, reminder that our bodies have limits. In 1983, on the People’s March for Jobs, I could do twenty miles a day carrying a banner (and singing sometimes) then get up and do it all again the next day, but not now.

On the principle that you should always listen to your feet, we decide that Jamie will go on to Barnes Bridge in a final gesture of defiance, while I beat a retreat to Ravenscourt Road tube and head for home, via Asda (as a sort of air lock back to domesticity).

To be continued…