My supervisor who supports me well, is moving from our current university to a new one and has asked me if I would like to move too. The supervisor has really helped me develop through my MSc and I am now on year 2 of a part time PHd.

The new university (Russell group) has a good reputation and potential in the field but my current Uni (1994 group) has a world class reputation in our field. Should I forgo the reputation of the current Uni to continue with my supervisor? Which is more important the supervisor or reputation of the institiution bearing in mind that I work part time and from a distance (my choice) with little face to face contact with my supervisor?

I'd go with the supervisor if your relationship/communication with him/her is good and things generally work well. I'd say uni reputation can be important (after the PhD), but really whilst you are doing it, key support comes from the supervisor, so I'd recommend moving with sup.(sprout)

I'd say go with the supervisor too, over and above academic reputation. I was in a similar position, nearly half-way through my part-time PhD, but my supervisor was moving 500 miles away, and I wouldn't be able to go there very often to meet him. In the end I decided to stay registered with my current university, partly because I rely on extra support as a disabled student which is easier to arrange locally, partly to make things like library access easier. My supervisor stayed as my official supervisor, communicated long-distance with me, mainly by email, and another member of staff stepped in as a joint supervisor when I reached the nasty writing-up stage and needed more face-to-face contact and more regular meetings.

Thanks for the advice both of you. I think you are right - should worry about finishing the Phd first.