We had tickets and seat reservations booked on this service in the First Class section (coach C). We arrived at the station with plenty of time and looking at the large departures board on York station concourse, the stated departure platform on the board was flashing and was now showing bay platform 1. The 3 coach Class 185 was already situated in bay platform 1 and all seemed well. A quarter of an hour prior to departure, a member of staff was seen moving around the train, ensuring the seat reservation cards were placed in the slots of the seats in question and with five minutes to go, the unit engines were started and the train internal lights came on. However 1552 came and went and no doors were opened on the unit and it was about 11/12 minutes after the supposed departure time that the doors were opened. When the unit set off, an announcement stated that the delay was due to "safety checks". If that be the case, why was an announcement made on the final section coming into Manchester Airport railway station that the delay was due to "signalling problems". Can anyone shed any light on this, as at York, trains seemed all to depart on time from platform 3 at York that platform 1 has faces upon on time? It seems strange the have two announcements on the same train giving two completely differing explanations for the delay.