I don't usually use parking at LHR (one-way car hire or wife drops me off) but I have just come to book parking for our first holiday out of T5 and was amazed at the price difference between T1-4 and T5.

For 12 days in April :-

T1,2,3 £162.10
T4 £134.60
T5 £264.10

How can BAA justify almost double the price from T4 to T5? I presume the cars all end up in the same car park, so where does the extra 130 quid go?