I saw this while trolling Facebook MArketplace. You don't see many GArvin's anymore and if someone has an affinity for these, it looks like it might be worth looking at. I assume they just mounted the vertical head to the overarm.
Yep, looks like a #13 plain Garvin mill, with a Dalrae milling head (http://www.lathes.co.uk/dalrae/) mounted on the overarm. The mill has the 12 speed feed gearbox on the back, added in 1909 I think it was. I had a #13-1/2 mill like it, except with back gears, and they are nice old mills.