Tim wrote:
I have an Oyster card with a Zone1-3 annual travelcard and something like
£15 of prepay on it

If I want to travel from Earlsfield (zone3) to Kew (also zone 3), going via
Richmond (zone 4), I only ever touch in and out in zone 3 so I am not
paying for my brief time in zone 4. However I have done what is expected of
me - touched in and out and carried enough prepay to cover my extension
ticket.

A colleague tells me that this is correct and that I am travelling perfectly
legally - can anyone here confirm this?

Theoretically, no, it's not "legal", as prepay is not valid SWT - so it
won't cover you for the short distance between North Sheen and Richmond.
To travel that way, should buy a paper extension ticket for North Sheen
to Kew.

The other legal alternative is to use your travelcard on the bus from
North Sheen, or travel to Kew Bridge instead (and use a bus if necessary).


--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London