..and it's not as if flying MAN-LHR-XX is cheap either, very often these fares are higher than flying CDG-LHR-XX or AMS-LHR-XX on the very same onward connections. However, on a disrupted day the CDG /AMS legs stand a good chance of being operated whilst the MAN legs have no chance.
To suggest ambling down to Piccadilly station, buying a walk up fare & then crossing London to LHR to try & re-book on a 12 hour flight, is quiet frankly ludicrous.
I'm with Shed on this one. All my hub connecting is done via ATL, FRA, MUC or ZRH & it works just fine for me.
However, if you like hubbing at LHR it's great for you to have that choice. Good luck.
My Chinese friend was convinced to go via T5 last year & the service / connection could not have been better for him, unfortunately, the same could not be said for his luggage.