Originally Posted by LonLH
Since I saw this post, quick reply:
1. Passport control and baggage in LGW could easily take 30 mins.
2. The fastest way to reach LHR from LGW would be train- Gatwick express. LGW-London Victoria (30 mins), from there an underground train or cab to London Paddington (15 mins minimum) and then Heathrow Express to LHR (15 mins).
Total travel time is 1 hour without waiting time, let us say waiting time is 1 hour total including passport control and bags. Since you have almost 4 hours between flights you should be OK unless there is a delay on the LGW flight.
The trains don't run every minute so your optimum times are somewhat off. You need to add at least 10 minutes for each train (walking, ticket purchase and wait time for the next train (both run every 15 minutes I believe).
The taxi queue can be bad at the wrong time of the day at Victoria as well.
I would say it's an 1.5 hour journey once the OP exits the customs door at Gatwick until he arrives in Heathrow. Add the price of the 2 train tickets x 2 and the cab fare ~10BPs, plus dragging luggage around through 2 connections and the 1.5 hour bus ride option starts to look very good IMHO.
www.nationalexpress.com