I believe it only ran on a limited basis, and took around 6 hours
Looking back I saw there used to be a direct Edinburgh - Wick service. Does any one have the timings of this service? Thanks
Found it the links are below.
Glasgow/Edinburgh to Inverness (2003)
https://web.archive.org/web/20031002055006/http://www.scotrail.co.uk/route04.pdf
Inverness to Wick (2003)
https://web.archive.org/web/20040613173255/http://www.scotrail.co.uk/route09.pdf