National Museums Liverpool (NML) is playing down the significance of the Duke of Westminster's decision to end his patronage of its development trust.

The duke, major general Gerald Cavendish Grosvenor, one of Britain's richest men, wrote to NML last month to announce that, after 17 years, he had decided to step down.

"It's a bit of a non-story," said an NML spokeswoman. "The duke was in a figurehead role, rather than being a nuts-and-bolts man."

Jane Sanders, a spokeswoman for the duke, said: "The duke's decision is entirely personal. He has an enormous number of commitments, and from time to time he reviews what he is doing and cuts back on some things."

The duke is the second high-profile figure to leave NML in the past eight months, after chairman Loyd Grossman resigned in May.