If the brother (Martyn) was in fact Cooper and the bad investment into a "property enterprise" with a lifelong friend who had ridden his trike with Moth as a child, was in fact the French property investment with his brother, then this would be a cruel (Greek tragedy of Sophoclean proportions!) irony indeed:
2004: Moth resigns from NT job at Plas-yn-Rhiw to embark on renovation projects ( Pen-y-maes and France?)
2005: Moth's falls through barn roof at Pen-y-maes while doing renovation work, perhaps to convert barn into holiday lets
2006: Martyn buys Chateau de La Barriere
2007: Moth remortgages Pen-y-maes and buys adjacent property to his brother's pigeonnier in Village de Dropt for 50,000 euros in hope of jointly redeveloping both properties and selling at a decent profit
2007: Sal steals £20k from Moth's parents to part finance French property purchase
2007: Martyn discovers theft from his and Moth's parents and ends contact with his brother, thereby scuppering the renovation project
2008: Martin Hemmings discovers that Sal has stolen £64k from his business over the previous 6 years
2008: Sal takes out £100k loan from relative of Moth's (Browne) to repay Martin Hemmings
2010: Browne's business goes bust and Moth's loan transferred to creditors who pursue the outstanding debt by attempting to repossess Pen-y-maes
1 May 2012: How Not to Dal dy Dir published by Izzy Winn-Thomas
July 2012: Martyn Cooper self publishes a book about a man from Burton on Trent returning to the UK to confront his past, entitled 'Stopcock'......
This version of events isn't quite the one outlined in TSP! Moth and Sal very much authors of their own misfortune!