Finding 7-track tape drives (Score 1)

The Computer Conservation Society software
preservation people in the UK
(http://www.personal.leeds.ac.uk/~ecldh/ccs/pres erve.html)
have been trying for several months to find
somewhere here that can read 7-track tapes with
historic software on. There is a tape I would
like to get read that is thought to contain the
source to the Supervisor for the Cambridge TITAN
system (http://www.cam.ac.uk/CambUniv/Societies/cucps/tit an/) -
the first timesharing system developed outside
the USA. There is another copy of this source -
a three-inch high pile of line printer output
from 1973 - which should at least help as a key
to identify character sets if the tape can be
read. (The appendix on character sets in the
Titan Programming Manual runs to 27 pages.) The
tape was copied from a TITAN-specific format
to 7-track tape before TITAN was shut down in
1973 so it could still be read afterwards, then
forgotten about until after Cambridge no longer
had any 7-track drives - then found again last
year after being supposed lost.

Have any copies of the source to CTSS (or, indeed,
any timesharing operating system that was
operational before that on TITAN went live on
20 March 1967) survived?