Originally Posted by NickB

Is that something that you know or is it an assumption that you make?
LGW and LHR are rather different markets: mostly point-to-point and competing with LCCs for the former; point-to-point AND transfer traffic competing mostly with full service carriers for the latter.
While there might be a case for extending an LGW product to LHR, depending on what product it is in the first place (in particular whether it is an add-on to or replacement of current catering product), it does not follow automatically even if successful at LGW.