There was a man and a woman going through the carriage saying "Tickets please." They had Oyster ticket readers with them and badges hanging round their necks which said "TIL Surveyor".

I didn't think anything of being asked for my ticket, until after they asked me to state which station I had got on at, and which station I was headed to. Having just compliantly answered their questions, I then realised that they had been recording this exchange on a digital voice recorder as they were doing with everybody else.

When I questioned what they were doing and who they were, they responded that they were not in fact ticket inspectors but were actually conducting a survey and that we did not in fact have to answer any of their questions.

I pointed out that they had invaded my privacy under the false pretence of being ticket inspectors, and that if we didn't have to answer their questions, they should explain this.

"We can't explain to every passenger that we are conducting a survey, Sir," was the response.

"So you see the problem with what you're doing then?" I replied.

When I asked if they had recorded my conversation with them about invasion of privacy and impersonating ticket inspectors, they advised me that they were not allowed to record it. However the recording of my voice saying where I got on and where I would get off, along with scan of my Oyster card, all without my informed consent and under false pretences - that was perfectly OK to them.

They also said that they've been doing this for a year.

At least one passenger heard my conversation and then declined to answer their questions or show his ticket.