Sunken treasures will be restored at a north Norfolk museum as it aims to expand its space and work in a bid to attract more visitors.

Schoolchildren will help clean an encrusted cannon – which could date back more than 400 years – and a rusty anchor, using scientific techniques at Sheringham Museum.

Both were found during cabling work for the Sheringham Shoal offshore wind farm.

The project comes as the facility at the Mo looks to expand – providing space for more exhibits, including the treasures, and a fourth former town lifeboat.

A major scheme would cost hundreds of thousands of pounds and could be built within three years, said museum manager Philip Miles.

An £85,000 Heritage Lottery Fund grant will prime the pumps to get the project off the ground.

The museum needs to apply for planning permission and grants to build the 200 sq m space on what is now a roof of the Lifeboat Plain building.

The cannon, which weighs half a tonne, could date back to the 1588 Spanish Armada invasion era and the admiralty anchor, which weighs a quarter of the tonne, could date from between 1750 and 1950.

Both items are kept in fresh water and the sea debris will be removed by an electric current.

The anchor will be cleaned at the museum and the cannon will be preserved at the Sheringham Shoal base near Wells. The wind farm has funded the preservation project and schoolchildren will be involved.

'It will put chemistry into action. If we don't conserve the objects they will rust away,' Mr Miles said.

He hoped the project would allow Norfolk to become base of marine object preservation.

It is hoped the new space would house the Atlantic 75 RNLI lifeboat which served Sheringham from 1994-2007; allow more people to visit the museum; and provide greater access to the centre's 15,000 archived items.

Mr Miles said: 'We have had lifeboats in Sheringham for more than 150 years so being able to display the Atlantic 75 with the other three boats at the museum would create a unique collection for Sheringham and the country. It is important for us to make our collection as complete as possible. Without the grant we wouldn't have anywhere to display the Atlantic 75.

'This project helps the museum become sustainable. We can drastically increase our visitor numbers because we will have more space to accommodate more groups.

'We will make ourselves more attractive for people coming to the town which will benefit the community.'

The museum currently houses the JC Madge rowing lifeboat (1904-1936); the Foresters Centenary (1936-1961); and the Manchester Unity of Oddfellows boat (1961-1991).

The Atlantic 75 was the first of its kind in Britain for the RNLI. It was replaced by the current Atlantic 85 boat in 2007.

The Henry Ramey Upcher lifeboat, in service from 1894–1935, is also on show in Sheringham and looked after by the town's preservation society.

Do you know of an interesting maritime heritage project in north Norfolk? Email sophie.wyllie@archant.co.uk