CliveL,
I should have kept a diary... never did.
According to the ConcordeSST site, the roll-out was on 20 September 1971, but (according to various internet items) Aerospatiale was already formed in 1970.
Looking at the general mess, the photo you mention (see below) was several weeks, if not a few months, before the roll-out.
Look closely.. I would say even the leading edges are not in place yet.
CJ