Travelled on this service tonight as I often do. Announcement as we passed Huntingdon that train would terminate at Peterborough due to a train fault. We arrived in Peterborough pretty much on-time into platform 1 and customers travelling north advised to board the train on platform 5. What I think happened was they terminated the 17:45 from Leeds at Peterborough. This train then took the passengers from the original 18:19 to Newcastle. The 18:19 then went back to London in place of the 17:45 from Leeds (hope this is still making sense ) All seemed rather odd to me, although fair play to VTEC for thinking outside the box or does this happen often? Also intriguing that the "train fault" still allowed us to arrive in time and then the train to travel back to London in passenger service.