Boltar wrote:

I don't use the jubilee much but the times I have been on that section
I've not seen any either. Also I can't see how someone would get on or
off a tube in a wheelchair train in the rush hour without serious
inconvenience to themselves and other people. Its hard enough for
mothers with prams.

If mothers with prams can do it, why shouldn't people with wheelchairs?
And why suddenly qualify with "in the rush hour".

People with wheelchairs travel on the accessible parts of the Tube in
the following manner: go through the wide gates, using Oyster card.
Use lift to descend to platform level. Get on train.
Repeat in reverse order at destination.