After examination of the official results from Football Lays and those reported from another Review Site, the cause of the major discrepancy in my results has been established.
On receiving a list of potential bets to lay from the Football Lays service, I laid some of the qualifying bets immediately at Smarkets (the betting exchange I used) as they fell within the maximum permitted liability. I placed the remaining qualifying bets at Smarkets at much reduced odds that corresponded to the maximum permitted liability.
Many of these remaining qualifying bets were matched, but virtually all of these were losing lay bets. The result was a massive discrepancy between my results and the official/other review results.
In the interests of fair play, the Football Lays service will be retrialled from scratch. In this trial, I will not leave any unmatched bets in the market.
Note Smarkets is a betting exchange like Betfair. Commission is only 2% as opposed to 5% for Betfair. Liquidity for the elite football leagues is good and for these leagues, the odds are nearly always the same as Betfair. Also, one can place bets lower than £2 at Smarkets very easily.