I came close to rewiring my rear foglight couple of years ago.
I had traced the failure to the control unit behind the dash. The pcb/logic board had failed.
In February I contacted Melvyn ( if anyone would have one......

).
Had to send photos as no ID numbers.
It was a factory supply unit.
By September, no signs, despite a query to the factory. They had replacements for 1997 or earlier but not post 1997.
Was told not suitable as a replacement. I was close to trying one for kitcar builders or rewiring to have power from dip/main supple circuit with an on/off switch to comply with only on when dip/main.
I examined the pcb and saw two solder joints that didn’t look good, so resoldered and it has worked since.The pcb would reset the lights to off when dip/main off so reselect was needed. It was to prevent forgetful people leaving rear fogs on when they deselected dip/main.
A typical Morgan experience re spares?