Hi Sheenboy. Mr ex-colleague Mr Grubby suggested i take a look at your post.
Helicopter operations within the London area are strictly controlled and, with one or two exceptions, take place on accurately defined routes. Those you see under the approaches to Heathrow will be vertically separated from the commercial jets above with never less than 1,000 feet between them. Over central London the Heathrow inbounds will be around 3,000 ft and the helicopters down around 1,000 ft so there is plenty of room between them.
The rules for helicopter operations within the London Control Zone are laid down the in the AIP.
Hope this helps but email me direct at
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