Mr Lammy is correct in what he says, but that does not make him right.
Perhaps he would like to take his stance a step further, and be available as a mugging victim, to avoid a poorer person going through the trauma. As an MP earning £67,000 a year plus expenses, having a couple of hundred lifted from his person is an expense he can bear more than the pensioner down the road.
So I am sure he will be making sure he is available - perhaps on his way out of Fortnum and Masons, where most of his constituents can probably not afford to do their weekly shop.