KLM quote flight durations (to Amsterdam Schipol) of around 1 hour 20 minutes from London City or Heathrow, and 1 hour 40 minutes from Glasgow International.
A bit pessimistic those times I would have thought, unless they are using an old wind up aircraft. London to Amsterdam should be about 45 minutes I would have thought.
Flight times are always quoted from 'push back' to gate arrival. The actual flying time from London to Amsterdam is under an hour but flight schedules allow for time spent taxiing and waiting in the queue for runway clearance.
I often fly Birmingham - Amsterdam and from push-back Birmingham to touchdown Amsterdam is 55mins. Because the more local flights then use a runway miles away from the terminal it takes 10 MINS to taxi to the building - no exaggeration!.