City types must hate the journey to LHR as many prefer the LCY JFK via EINN on a 318 which is far slower than LHR JFK on a 747 ( M.79 v M.86 ). I would have thought if you could get around planning, clearing security at LCY then helicopter to LHR T5 into lounge airside for connecting flight must be doable. BA even have the pilots to do it.
MAN LHR won't work as you can't compete with a 319, city centre to city centre .........you can't compete with rail.
Now it's about time LHR LGW got the airlink back possibly a triangular service with the city.
Our wonderful transport secretary is MP for a W London constituency and has stated in Parliament that she dislikes helicopter noise over London however.