GB
Travel frok LHR to London proper is usually quite busy but, in my experience travelling the other way it should cost no less than £35. What time do they arrive, because it may be more practical to hire a people carrier and pick the whole lot up in one. not to mention cheaper.
I would try Travel Point (02075822174 /
www.travelpoint.co.uk /
travelpoint@btconnect.com) who I have heard good things about but also offer one flat rate to any airport in their literature.
Worth a try.
Jess