1996 Toyota Camry 2.2 (JDM)
Happily they pulled into the RH lane at the next roundabout, so I was able to get a vaguely reasonable shot off the dashcam as I slowly drove past. Looks to be one of the Japanese-spec narrow-bodied models.
DVLA says first registered in the UK back in 2008. The 'AV' registration makes me wonder if it came here through Alconbury with American service personnel.