Purrrrrrr7777777
The other noticeable "gap" is the lack of BA flights from Moscow early morning as the current options allow evening travel only.
....something that BA have been trying to get for many years now.
AFAIK there are issues over security for the aircraft (and crew) on a nightstop that need addressing. Add to that that the Russians don't want to let get go of the highly lucrative ealry morning business traffic and you can begin to see why the progress has been very slow.
There were rumours a few short months ago of a late LHR departure arriving at say 0300 local with a, say, 0700 local return. ie an extended turn around for the aircraft, a 24-hour crew slip - I would guess on the 757/767.
Watch this space......