But this isn't the case, it's just that when operated nowhere near these limits (which the Trident was most of the time - say on domestic flights) the 'better' performance demonstrated might mistakenly be taken to be the yardstick of acceptable performance.
My father, who sadly died this year, was foreman of the BEA metal plating shop at the Heathrow Engineering Base from around 1959 until he took early retirement at the BEA/BOAC merger. Being his son I was 'plane mad and remember a BEA Trident calendar he acquired for me in around 1964. Fabulous.
During the school holidays he would often take me to work with him and I'd spend the day in the BEA staff canteen at the end of 28L, as it was then, happy with my binoculars and Ian Allan books. I well remember in the late '60's that in comparison to most other types the T1/T2 appeared to have a sparkling climb performance. I well recall a TWA 707 coming off 10R being at only about 50' as it crossed the threshold and barely climbing as it disappeared over Hounslow.
Slightly changing the subject, I also recall seeing on a dark morning a 707 parked outside what was the Air India hangar south of 28L, starting up. It was directly tail-on to me and I clearly saw the combustion chambers in each engine lighting up, making a ring of bright dots. The memory is distinct and clear, but given that they must have been hidden by the turbine blades I have no idea why I should have been able to see them.
I have to say, though, even though this is a Trident thread, that to me the best-sounding aircraft at ground idle was the Iron Duck. It reminded me of a bronze bell. I'll never forget.