Thanks Mark,
Roland Ranfft kindly replied to my email with the info - it's a Val. 61. I can't believe I missed it, there is one as clear as day on the OTD/movements page - doh!!

I've been researching this 701, and there seems to be so many blind alleys and false summits, especially as the 701 as a model ref. no was in use from pre-1938 to at least the late 60's. where the 60's catalogue states it has a Val. 76.

Not sure about you're observations Mark, Dr. Rannfft identifies both as a V.61.. I have a better 'top down' photo, and the m'ment is the same as the diagram.
I know that David D has/had one of these & his m'ment is identical.(same bridge)
I'm just waiting for David to give me permission to use his photo & then I can upload all my research.

Markings on it are: SWISS MADE 145688 (I think it’s a ‘1’ at the start)

Cheers
Stewart

: I'm not as familiar with the pocket chrono movements I'm afraid,
: but Jeff identified a later 701 as using a Valjoux 5:
: http://www.chronocentric.com/forums/heuer/index.cgi?page=1;md=read;id=4265

:

: But that doesn't seem to be what is in the watch you pictured
: Stewart. It's not a Vj22 either, that was used in some of the
: early pocket chronos. The bridge looks like a more recent
: replacement, it doesn't seem to have the age of the hammers and
: the other components.

: What's stamped by the regulator? Looks to have a serial number and
: maybe something else - any maker's mark there?