Re our timeline: 1994/95 - Sally and Tim Walker sell house in Staffordshire, leave jobs, move to rented house in Criccieth (BBC)
I've looked into this.
Moth's grandfather was a contract plasterer who lived in a modest terraced house in Burton. He had a son and daughter. The son (Moth's dad) followed his father into the plastering business. He seems to have taken over the business when his dad died in 1973 (his funeral was very well attended, and he seems to have been well-respected).
Moth's parents lived in a 5-bed detached house - I don't know whether or not they owned it. Perhaps Moth worked for the business as a plasterer, although I have no evidence that this was the case.
Anyway, in 1994 the Inland Revenue presented a petition to wind up the company, presumably because it was unable to meet its tax bill. By this stage, Moth's dad would have been almost 60. A tax demand is perhaps a common reason for companies to go bust? The company seems to have continued to trade at least until 1997, as there was a further winding up order in that year.
That might explain why Moth found himself jobless in 1994/5, as the company could no longer afford to employ him (assuming he did indeed work for his dad.)
(Companies go bust all the time, and there's no suggestion at all that Sally was the bookkeeper, before anyone adds two and two to make five 😁)