Transportation from London Gatwic Airport to Lancaster Gate station

There is NO public transport in London on Christmas Day. If anything I would seriously recommend looking into changing your arrival date if you have any option at all. If not then I would recommend prebooking a shuttle service or taxi all the way, although that might be expensive.

Here is a quote from the Gatwick Express Web site: 25 December 2010 Due to essential planned engineering works, Gatwick Express will be operating a Replacement Bus Service on Christmas Day. London Victoria to Gatwick Airport: Service is half hourly commencing 06 30 until 16 30 then a 16 45 vehicle is the final vehicle deprture. Gatwick Airport to London Victoria:
Service is half hourly commencing 06 30 until 17 00. Take the above-mentioned bus to Victoria. Take a taxi from there directly to your hotel.

I was going to tell you the same thing as Tim did so won't repeat it. Here is a number you could call now regarding booking a taxi to pick you up at Victoria Station 011-44-20 8901 4444 here is the website regarding taxis..http://www.tfl.gov.uk/gettingaround/taxisandminicabs/taxis/1136.aspx

If you want door-to-door service from Gatwick to your hotel, book a private car service. It will be a lot cheaper than a taxi. Just Airports (www.justairports.com) offers a discount for paying cash. The cash price for a saloon (sedan) from Gatwick to anywhere in postal code W2 is £47.

I would expect the car services to charge more on Christmas Day, maybe 50-100% more. Traffic should be light, anyway.

Just Airports confirmed a 50% surcharge on Christmas Day.