Thanks to all who replied.

The consensus seems to be that ideally I should protect
against UV. For the very short lengths of exposed cable
we are talking about, mechanical stresses are not an
issue, so I wondered about this as a potential solution:

http://www.tlc-direct.co.uk/Products/TLSAT19.html

(self amalgamating tape).

Although it isn't described on the tlc site itself, a
google around the web suggests this stuff is suitable
for waterproofing and UV protection. Anyone have any
experience of this or opinions on its applicability
here?

Thanks,

Ian