Airlines that fly to Edinburgh from London area airports

A good friend will be coming to visit in October before she flys up to meet her family in Edinburgh.  I'm just wondering which airlines she should be looking at that have the best deals. Also an airport that is not to far from me in Surrey would be great.  (We are about 40 min from both Heathrow and Gatwick)   

Any suggestions would be very much appreciated.

Thank you

BA, Flybe, Easyjet, BMI and I think Ryanair.

Air France flies into City.

to Edinburgh? BA definately has flights from both airports to Edinburgh as does BMI. The cheapest way would probably be Easyjet (Ryanair is cheap - but leaves from Stansted in Essex and goes to Glasgow-Prestwick which is an hour and a half train ride from Edinburgh although if you show your ticket, you get 1/2 off the rail fare. There is also a bus link).