“Our members are 84 years old on average. Their short-term memory hardly works, but the long-term memory is still active.

“They know the green and yellow bus sign and remember that waiting there means they will go home.”

The result is that errant patients now wait for their trip home at the bus stop, before quickly forgetting why they were there in the first place.

“We will approach them and say that the bus is coming later and invite them in for a coffee,” said Richard Neureither, Benrath’s director. “Five minutes later they have completely forgotten they wanted to leave.”