Allright - but we can confirm, that the lines are not missing because on the airport-diagram there are no taxi lines, also not on the chart of the AIP. And honestly, normally you follow the lines directly in the aircraft and not with the finger on the chart 
The important point is, that you´re on the right taxiway
The letter are clear I guess and for more details, you can “zoom” into the parking-stands:
I can´t find your example screenshot in the EGLL chart - where is it?
Cheers,
Richard