Fears that the Art Fund prize would favour galleries and art collections were dispelled last month when the shortlist for the prize was announced.

The four museums selected to compete for the £100,000 prize are: the British Empire and Commonwealth Museum in Bristol for Breaking the Chains; Shetland Museum and Archives, Lerwick; the Lightbox gallery and museum in Woking; and the Wellcome Collection in London.

Ken Arnold, head of public programmes at the Wellcome Trust, said he was excited and proud that the collection had made it on to the shortlist.

"We feel as if we are still the new kids on the block," he said. "We have been open only a year and there is much more that we want to do." Arnold added that the strong shortlist illustrated the sector's buoyancy. "The spellbinding variety makes the judges' job even harder," he said.

Broadcaster and chair of the judges, Sue MacGregor, said they had been impressed by the museums that they had visited. "I am delighted that the shortlist continues our theme of diversity, distinctiveness and excellence," she said. "Any one would be a worthy winner."

The six museums and galleries that failed to make the shortlist were: the British Library for Sacred; the International Slavery Museum, Liverpool; London Transport Museum; the National Army Museum for Helmand: The Soldiers' Story; the Pier Arts Centre, Orkney; and Topsham Museum, Exeter.

The winner of the prize will be announced on 22 May.