I have a feeling both myself and Bluloop owned this car about 6 years ago.
Sold it to a young guy in Glasgow, but at that point it had a Polo 6R converted rear bootlid.
The timing belt was done in about 2015 by my pal - if you can check the service book and confirm it was done by ‘Tornaveen Engineering’ I may be tempted to buy it back.
From memory, it's a captive nut. But getting the holes to line up was the trouble I had. Try loosening off 37 and have another go. You may even have to jack up the engine or loosen off the engine mounts. Have fun...
@Rich your thoughts?