"MIG" wrote in message
...

They are apparently "up to" £7. But given that the reason for
charging maximum fares is that the system doesn't know where you went,
on what basis can it ever calculate a different maximum fare from the
maximum maximum fare?

I think you might be reading too much into 'up to £7.00'. There are only
two possible LU entry charges (aka max cash fares), peak £6.00, and off-peak
£4.30.

AIUI higher max cash fares are only charged at origins outside the zones
when NR fares are involved.

The £4.00 entry charge for an uncompleted journey prior to Jan 2010 was
potentially less than the correct fare in the peaks, which is why they
changed it to £6.00

Paul S