[Craig T]

Originally Posted by tevake

The double decker busses are a good way for a quick relaxing look around.
They narrate on board with lots of info. If it's dry go upstairs.
The tube/ underground is a good way to cover distance within the city quickly.
Mind the gap.
The museums are so vast that a quick run thru may be frustrating or a little taste of future delights

Cheers Richard

Nice idea for an overnight layover, but not for just 8 hours. Figure 1 hour through customs, 30 minutes to catch the train, 45 minutes into the city on the Express Train from Gatwick (if timing is right for fast train)…than 30 minutes back to Heathrow on the Tube 90 minutes before his flight. Account for walking time to and from a Pub and he'll be lucky to have 3.5 hours in London.

I would do it for sure, but know the train schedules in advance and try to google the in-city destination.