The issues seem to arise because the Gambling Commission can't come up with a policy that makes sense to machine collectors / enthusiasts?
The GC has never been expected or obliged to make policy - all it does is interpret and enforce legal statute made by the government at the time, this includes enthusiasts by default as no distinction was made at the time. I don't envy them the thankless task of trying to regulate the industry, while also being obliged to keep on top of all the traders masquerading as collectors (yes, they are out there).
I can't buy ROMs for a 20 year old machine, or a 20 year old machine from a collector - but can buy hoppers, noteys, mainboards, and infact whole working machines which are in current circulation?
No, you can't SELL roms for any age of machine, nor can you sell a complete gambling machine - especially not one in current circulation - without the correct license or permit. This is because:
1. Roms and software are the parts that definitely "Affect the outcome of the game". Other parts (with arguable exceptions) do not and so you can sell them freely.
2. You can't SELL any gambling machine of any age, because it is and always will be a gambling machine even when it is effectively obsolete. The Act does not make any provision for age and it could be problematic if it did do so.
You CAN still legally buy any part of, or complete gambling machine, it only becomes a criminal offense if you then use that item other than in accordance within the law.
I just can't understand they way they operate, it defies logic. It seems to play into the hands of 'dodgy' operators but screw collectors at every turn.
"Dodgy operators" are often taken to court, if you can find me any case where a genuine collector was actually prosecuted I will climb onto my roof and read from 50 shades of Gray through a load-hailer, until such time as the police come and remove me.

My main point though wasn't about the GC, it was about Nick not getting himself in hot water with his employer. I mean if I ran a machine supply business, and someone just started and was asking me about buying / selling parts, I'd be a little wary. There was a local example where a technician from a local machine operator was running machines in pubs himself without permits, using spares from his workplace. Not naming the operator but I know the person involved.
This is exactly why some operators will skip machines rather than sell or give them away - they are cautious of unlicensed buyers selling them on or using them illegally, and getting them into trouble as a result. It's very easy to see their point.