Yup - this was totally left of field. I did a routine alteration to a dataobject - no JS involved - that was it... Did a dev/build and ?flush THEN I got this: Uncaught ReferenceError: jQuery is not defined on the admin section - fine on front end.
What was also odd - when I viewed the source is the file was there and accessible??? In the end I took the nuclear option and reinstalled everything. But that to me is not a sustainable solution for what I have a nasty feeling will happen again.
SO... Question is - why did this happen? Is this an SS bug? Has anybody had a similar thing happen to them? Grateful if you could share your experiences and solutions.
Thanks in advance.