Basically LCY is only useful if you live or work anywhere near it
You've made my point in a nutshell - the OP says he's (she's?) only 5mins from LCY. That's what I was addressing.
Certainly doesn't take 45 minutes.
I meant at LCY, from check-in to airborne - think LHR/LGW would be hard-pressed to often match that.
Don't get me wrong, I think that Heathrow particularly, does pretty well, especially considering the parameters that've been set out for them. I quite enjoy my transits through LHR, aircraft-watching, and people-watching too!