1) This would probably have been better placed in the London board here on FT.

2) 50 minutes should be OK even if you have to collect bags, but obviously any sort of delay could wipe out this advantage - LHR is very congested especially in the morning - they often just keep flights on the ground in Europe until they know when the runway slot will be available. If you're travelling in Economy, expect to have to check those bags (13lbs limit is typical).

3) You might be better off just booking a new flight from wherever you're coming from in Europe to Stansted, especially if Easyjet do the route (Ryanair is the other big LCC, but they get very mixed reviews). You'll save yourself 2hrs in a coach on the motorway and that's got to be worth something...