"Acquired on the London art market": known before 1970?

I was interested in the collecting histories of pieces at the Bonhams sale this past week (April 29, 2009).

Christos Tsirogiannis in Cambridge has drawn my attention to six lots.

• lot 48: Roman limestone funerary male bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", £13,200
• lot 49: Roman limestone funerary female bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", £13,200
• lot 50: Roman limestone funerary male bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", apparently unsold
• lot 51: Roman limestone funerary female bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", £6,600
• lot 52: Roman limestone funerary male bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", apparently unsold
• lot 53: Roman limestone funerary male bust, Eastern Mediterranean, "Acquired on the London art market in 1998. Accompanied by a French passport", apparently unsold

They seem to form a coherent group. Which London dealer or gallery handled the pieces in 1998? What was their collecting history prior to 1998? Have they been in a French collection?

What does the "French passport" imply?