I have hundreds of tracks that need the Title Trimmed at the front and the rear:
e.g. = David Bowie - Jean Genie - 1972
convert to
Jean Genie.
Basically a mid string sort of solution.
Try an action of the type "Guess value"
Source format: %title%
Guessing pattern: %dummy% - %title% - %dummy%
If you want to preserve the information of artist and year, then use
Guessing pattern: %artist% - %title% - %year%
Brilliant ohrenkino, and of course the penny drops when you see the string - It works. I have just realised that I need the artists and year parts of the string to populate the artist and year fields. Any help on this ?
Yes, instead of the first suggested guessing pattern, use the second:
The source string stays the same.
Thank you so much that has worked 
Saved me loads of work and i understand the %dummy% variable now.