Antigua
I don`t think tech stopping for fuel is the issue here, if you thought there would be a delay at LHR then more fuel loaded would have being a good idea (aic 131). If the r/mtom was restricting then maybe offloading frieght/bags/or even bars(as I have done in the past) may help. But as has been said we do not have a crystal ball so it is possible to get into the same fuel situation as you had and I`m sure we all have been there.
What I do find strange is the statment that once in the hold at LHR we have no fuel to divert (does this happen often?). I know that since the introduction of JAR we can in exceptional circumstances land with final reserve fuel (30 mins) when an approach is imminent etc, etc (ASR required in our company).
I would have thought with the variables at LHR it would be possibly not a good idea to excersise this option and to divert when down to no less than 30 min plus diversion fuel.
Having said that I can also say that hindsight and a perfect world are wonderful thing`s.
A very confused Fish!