Paul Terry wrote:
Around half the passengers coming into Heathrow are British
people returning from their holidays, not tourists visiting.

I don't know where you get that statistic from,
but I don't think its correct.

It is close:
http://www.dft.gov.uk/stellent/group...ats_505957.pdf
"At Heathrow, in 1999, 42 per cent of all passengers travelling to and
from the airport were foreign ..."


The National Statistics' Office Travel Trends report for 2000 says
....
Heathrow accounted for over a half of all visits by overseas
residents travelling to the UK by air.

Good data. Thanks.


When I go from Tooting to Heathrow [...]
I get a taxi every time.

That's fine, since you can clearly afford a taxi.

% Mode of transport
Heathrow
35 private car
4 hire car
26 taxi/minicab
14 underground
7 rail
14 bus/coach

All airports surveyed
48 private car
3 hire car
23 taxi/minicab
6 underground
10 rail
10 bus/coach

Lots more detail provided in reference given above.