Hi v4rley
Thanks for the reply.
Called it a day earlier as the thermostat replacement had been a bit more time to complete than I thought it would be, but go there in the end.
The new part has the same plain fitting on either side of it, so I think your right and it just pulls off, as there is no notch or indent that would allow the pipe to click into place.
The vacuum pipe appears to sit over a rubber grommet (to seal the line I assume). Might try getting it warm with a hot air gun, and then tugging a bit harder to free it off. Found a YouTube video showing how to replace the line that goes off to the engine pump side, and was just pulled off as you say.
Will report back once its been removed.
Regards