We send quite a few clients through Heathrow with our business. Until now have been sending out Purple Parking discount voiuchers for those driving (by car, poor folks) to the airport. Just asked PP if they will do bikes but they won't (and are some way off airport) but I may have found another closer parking outfit who will. Am negotiating now and will post any result. I think that the odd day or three at the airport is probably worth the punt in the T4 bike parking (CCTV, normal place for cops to stop and much less hidden away then the T1 parking as far as I can tell should equal a safer place to park) but, for those of us who want to park for much longer, something more secure needs to be sorted out, the snag being that it'll cost something to do so in secure parking. It's got to be worth investigating so more shortly, when/if I get a result and have tried it....