When using a hotel's "house car"...

It depends on the distance and his or her demeanor really. And, if he lifts any of your bags. I'd say at least a dollar a bag. Distance might be anywhere from $1 to $5. If he's overly courteous and makes your wife feel elegant and special, then even more. My gut says, just tip the guy $5 and he'll be happy. But, if he's truly nothing special, $2 or $3 is enough. It all depends on how good you feel his service was to you and your wife.

Vero is right on here. Good adice all around. The more time spent with you, the bigger the tip.

$5.00.

In London it is regarded as low-class, or a noveau-riche thing to do (tipping). That is not to say that a fashionable London establishments, such as Hakkasan, Taman Gang, Nobu, and Zuma, it is not expected, but at the higher class places; like Le Gravoche (sp.?) and such the like, it is still very much the old ways, of tip=you do not know what you are doing. (even though the fashionable places are more expensive than the high class places) In America I ahve found things to be different, tipping seems to be always expected, reagardless of quality of service.

I don't care for the tipping system myself, because in America, it's deviated so far from its intended purpose of simply rewarding quality service... now people treat a tip not as a nice gesture, but as something obligatory and expected, and try to guilt trip people into doing so. It also seems to be getting out of hand as to who you're expected to tip and how much (for waiters it's always been 15%, but now they want to claim 20% is the standard, and how that's only the bare minimum amount for a tip that will be "tolerated" without making you look cheap or boorish, etc). I just try to avoid using services with a tipping culture (ordering to go instead, carrying my own bags, etc), but when I do I'll do 15% for waiters and toss a few bucks at other services with well-established tipping customs (i.e. pizza delivery, valet). I won't tip, say, a bathroom attendent, because I can wash my hands and get a towel on my own just fine. That said, I'd just give him a few dollars assuming he has to drive you a good distance and is generally friendly and helpful. I don't have experience here; that's just how I would go about it.

Yikes.  I asked a similar question awhile ago and got almost opposite advice from Kalra.  Will be in London, in two weeks, dining in some of the very establishments you mentioned.  Won't know what I'm doing.  

Which places will you be going to when in London, also where will you be staying?

Staying at the Marriott Hotel Grosvenor Square (on points).  Dining at Hakkasan, Nobu, Sketch, Gordon Ramsey's at Claridge's and some others.  Don't have my file handy.  Any advice?

How old are you? You will be quite surprised at how young the crouds are at Hakkasan (excellent), Nobu, and Sketch (By the was, have you booked at Sketch? You will need to, unless you know Mourrad Mazouz himself. ) I personaly hate Gordon Ramsay at Claridges, but then again I am 16. I also think that Gordon Ramsay on Royal Hospital Road in Chelsea has far better food, the only think is you dont get the opulence of Claridges, Petrus and  is also a lot better for that knid of place. For lunch do try places like The Ivy and J. Sheekey. Also Beibendum, though most people think it finished, along with the rest of the Fullaham restauraunt scene (along with Blue Elephant, oh the agony. ) I still feel you cannot beat the oysters there. Also, if you are quite young, do check out Tramps, Rex and Attica, for clubs, they are the top ones at the moment. (The reason being; Sketch is somewhat of a club after 11 (I think) when the music begins). Do not be fooled, Sketch has the repute of being a fine resteraunt (which it is - dont get me wrong) but it is also a bit of a bar/club thing. Sketch - you must go. (as long as you are under 30 ish)

Taman Gang is supposed to be the next Hakkasan, but when I went (about 4 weeks ago) it was quite empty, it has much more of a middle eastern flavor in terms of decor, and a little more light (if you can get any, in these places. ) The food is still oriental though, a little better than Hakkasan, but then again about 5 times the price. Actually, Taman Gang is just next door to the Marriot on Park Lane. So you must go.

Oh, and skip Nobu for the Japanese, go for Zuma in Knightbridge, with these places, it is like a rat race, and whichever is the latest is deemed the best...

Oh and if you like Indian food, go for The Mint Leaf in Victoria, it is like Hakkasan.

Oh sorry, I think its a different Marriott (for Taman Gang)

Thank you, Styleman, for the well considered advice.