You are getting confused by the difference between block time and airborne time. Airline schedules are block time i.e. time from start of push back or taxy to time on chocks at destination. The ground time - that between push and take-off and landing to chocks on is known as ground time and varies, often by known ground times at the relevant airfields and time of day (rush hour or not). Hence a LBA-LHR flight has a scheduled time of ca. 1 hour, say 10 minutes ground time at LBA and 15 mins at LHR but a flight time of 35 minutes.
In the case of LBA-MAN the ground time would be in the region of 20 mins and flight time 15 mins (can you do that in your car?).
If LBA-BGI were possible the ground time would still be about 20 mins giving a flight time of 8.40.
beaten to it by 7 mins!