How did Gail miss noticing Martin's car parked outside when she went round to Rebecca's flat to return the purse?
It was clearly visible through the window on an earlier occasion, when Rebecca and Martin were deciding to go out and buy cushions together.
So his car must have been somewhere outside when Gail went round.
Also, how has Audrey (who supposedly is practically penniless and struggling for money) suddenly managed to upgrade her car (from a modest little Renault) to a big posh BMW? 