Challenge: What car is this ?

[Lennart Sorth]

I have recieved this request from Davide Montini :

# My name is Davide Montini and I collect postcards featuring F1
# and Sportscar cars.
# I have found this postcard...it seems from 1965, 1966 or 1967.
# It seems Monaco: I don't know the exact year, the driver and if
# this F1 or F2 or F3.
#
# Could You help me  ?
#
# Kind Regards
# Davide Montini (Torino)

[Lennart Sorth]

It looks like a MS5/6 car (?) - at least not F1.
French advert, and guard-rail supports Monaco tjheory.
Matra didn't race that many formula cars with #15 on them.

My closest suggestions are:
Formule-2 1966-1969
=====================
1966: 11/9 Monthlhery , #15  Hahne, MS5-BRM - finished 10th
1966: 30/10 Brands Hatch, #15 Ickx, MS5-COS - finished 4th
and
(1968: 3/6 Crystal Palace, #15, Pescarolo, MS7, retired)

But since the driver apparently is waving (and driving rather slowly) it suggests a good performance, and this is the lap-of-honour (?).
If I search for a Matra formula 2/3 car, which finished at Monaco, which COULD be number 15, I'm left with only this one:

1966 21/5: Monaco , Jaussaud, MS5, finished 5th