The short runway at Edinburgh and the heavy traffic /shuttle on that route was one of the reasons for the 3Bs boost engine. A boost failure on a evening flight to London meant a lot of people had to get off .
Watching Trident ops back in the day at LHR they didnt look like they performed as badly as they apparently did , I suppose it was the very long runways and the other aircraft a round that made it appear they were pretty normal. Unlike BEA Comet 4Bs that really did reach for the sky with perfomance only bettered by the MD80s and 757s although varous peak time oddities like Sabena 707s only going 180 miles or so.