Originally Posted by Volvic
If my memory does not fail me, I noticed a funny thing. If you miss a HEX the next can be a Connect but if you take it you arrive at Paddington basically at the same time of the following HEX.
After coming out of the Heathrow tunnel the Connect goes on to the local tracks of the Paddington main line and stops at the various suburban stations. The HEx takes the express tracks, shared with the long-distance trains coming in to Paddington, this is how it catches up with the Connect.