It turns out that if one cycles up through MOD Abbey Wood before 0900 local time, there is in fact a very large traffic jam of cars waiting to get into the secure car parks.
Unlike Bristol City "secure" car parks like the infamous Trenchard Street car park, where you clearly have to have your name and date of birth tatooed onto your neck to get arrested for stealing from cars, this MOD facility is pretty locked down: guards, ID, and a covered bridge to get to the offices. The Abbey Wood setup is to avoid car/truck bombs: it was built in the early nineties when the Provisional IRA were regarded as a terrible threat, rather than a terrorist group to fondly reminisce about. All parking is a long way from the offices, instead it is close to the ill-fated Cheswick development.
Getting through the security checks to park is pretty slow, hence the tailback all the way to the A4174. Hence also the cars blocking the bike lane. Perhaps we should demand hatched yellow junction markers here, if only to make the junction more slippery and entertaining in ice.