If you could bring Concorde out of retirement and use it on the JER-LGW the flight time STILL wouldn't be much different than what a Q400 could do it in. Indeed it might even be quicker if you were to do a tight visual circuit at destination.
The point is these are tools for different jobs. The Q400 is IMHO the best tool for short sectors whilst the 146 does a better job of the long sectors - Period
Those Q400 pilots who feel the need to make out that the Q400 goes as fast as the 146 etc.etc. need to understand that -
a) it doesn't
b) it doesn't matter anyway
c) the Q400 is good at what it does so stop walking around with a chip on your shoulder.
d) dispatch figures are fudged in the favour of the Q400 for reasons I have given earlier.
e) the 146 makes the company a lot of profit on the Spanish routes, just try and travel standby on one and you will appreciate this.