Originally Posted by bgriff

The way that the drive-through check-in is set up, if your driver enters the area where you buzz up to be let in and the agent determines you're not eligible, it could be quite a project to get back out, especially if there is a car waiting behind you. So they may just let you in even if officially you're not supposed to be allowed.

I wouldn't necessarily press your luck, but just an observation ...

The drive through check-in is cool and fairly unique, especially with the staff taking your luggage out of the trunk of the car for you as if you were arriving at a luxury hotel, which AFAIK doesn't generally happen anywhere else, even if flying first. But it's ultimately not a big loss to miss it, and if you were going to choose to arrive at LHR via train there's no way to make use of it anyway. The real value proposition is the private security channel, which is definitely available to PM/DM flying coach via the magic door in the terminal, and the Clubhouse, which (despite Virgin's marketing implying the Upper Class Wing feeds directly into the Clubhouse) is on the other side of the terminal and requires a walk to get there for everyone.