@Eidolon,
This gadget converts VGA to PAL or NTSC composite :
https://www.amazon.fr/LEDMOMO-1080P-...ronics&sr=1-96
Found it on Amazon.fr, just lookup the product on Amazon UK
Of course you will need to retrieve the RGB + Sync from whatever connector/pin-out your computer uses & connect to the standard VGA pins which will input the converter.
No ties to Amazon nor seller
Regards
jhalphen