Responding to a Freedom Of Information request, the FSA said no mystery shopping exercises had been carried out since March 2010.
Hector Sants said that month that the FSA would make more use of mystery shoppers.
The FSA said it was a tactic used “in the right circumstances”.
At the time, the FSA faced criticism for not using the technique more routinely as part of its day-to-day operations.
Sarah Brooks, director of financial services at Consumer Focus, told the BBC: “It is a little surprising that the FSA hasn’t placed more of an emphasis on mystery shopping, which can be a useful tool in identifying consumer detriment.
“We accept that mystery shopping may not provide the hard evidence needed for enforcement action. However, it can act like a canary in a mineshaft - an indicator of problems.”
