In message , at 14:38:19 on
Thu, 29 Dec 2011, Graham Harrison
remarked:
And how many airline passengers have Oyster cards?

Quite a few I would imagine, given the number of people living in
Greater London who have them and who might well be flying out of
Heathrow.

And the thousands and thousands of staff who work in and around
Heathrow.

Why are the staff taking trains from one terminal to another? If
their job requires moving around the airport I'd expect the employer
to provide an [airside] alternative.

Not everyone has an airside pass. In fact, these days, they try and
restrict the number.

So this is landside staff who have jobs in multiple terminals. Seems
like a small subset, being that far away from anything airside (and most
airlines only have check-in staff in one terminal).
--
Roland Perry