Portfolio-holder Bryony Rudkin said the proposed development of the High Street would be a major step in improving the town’s cultural offering.

She said: “The museum is a much-loved building and we are very keen to retain its great atmosphere but it is looking a bit tired.

“There was some work in the 1950s, but there have not been major changes to the building since it was put up by public subscription in the Victorian age.

“We want to really take this on and create a real attraction that will bring people from a wide area to the town.” She said the council would be looking to get about half the £20 million cost from national bodies.

“We will be bidding for about £8million from the Heritage Lottery Fund and £2 million from the Arts Council.

“The rest will come from other sources – some from the council and then from other donations. But the appeal to buy the Ipswich Art School was very successful and we hope to repeat that on a larger scale,” she said.

Ipswich MP Ben Gummer helped to develop the Arts School for the town and welcomed the move.

He said: “I am delighted that the Colchester and Ipswich Museums Service is pressing ahead with this proposal. Our town’s museum is a real asset for Ipswich.

“I was excited to be part of the Art School Project and I am thrilled that this ambitious proposal is now going forward – it is just what Ipswich needs.”