`What is the best also fastest way to travel from Heathrow to Windsor for six people?

Best and fastest inherently means not cheapest - - I trust that you understahd this.

That said, I'd request a quote from Eddie Manning at http://www.limo.co.uk - - you can be reasobly sure that he/his drivers will treat you right. Probably under 25 GBP per person (I'm just guessing).

Best wishes,

Rex

The local taxis around here (Windsor/Maidenhead) would charge you about £20 to £25 (total, not pp) for a pickup at Heathrow to Windsor. Some of them could handle 6 of you, as long as didn't have much in the way of luggage. If you are all carrying some kind of luggage, you'd need two cabs, so double the rate. And will you need to get back to Heathrow or has HRM invited you for an overnight visit?

25 GBP is so totally out of reason - maybe Rex is smoking something tonight

As BTilke says, a local taxi would be able to accomodate you unless you are schlepping all of your luggage. If this is for a layover between flights,there are left luggage facilities at LHR.

If, on the other hand, you are staying over in Windsor, you would do well to pre-book a car service and they will use a mini-van type vehicle w/ space for you and your bags. Even a van will only be 20-30GBP total (not perperson).

Or of course - you can always take the local bus for a few GBP per person.

Most taxis only take up to 5 passengers. If you want one for 6 you would be wise to pre-book.