The museum, which houses a replica of the Colossus code-breaking computer, has been in talks to preserve its place as part of the Bletchley Park story.
It is strongly against the trust’s plans for the “fragmentation” of the park.
The National Museum of Computing is an independent charity that occupies Block H, a hugely significant part of Bletchley Park since it is the home of Colossus and the world’s first purpose-built computer centre.
It currently pays rent and utilities totalling more than £100,000 per year to Bletchley Park Trust.
In a statement issued today (Monday), TNMOC acknowledges the need for change but outlines its opposition to the plans of the Bletchley Park Trust.
It says: “One facet of this fragmentation is the removal of TNMOC’s Colossus and Tunny Galleries from Bletchley Park Trust tours and the isolation of historic Block H.
“TNMOC trustees are disappointed that Colossus Rebuild is not to be interpreted to the public as an integral part of the Bletchley Park story as envisaged in the Bletchley Park Trust’s successful Heritage Lottery Fund bid.
“Our "Our records show that the numbers of Bletchley Park visitors coming to Block H to see the Colossus Rebuild are declining as a direct result of Bletchley Park Trust actions. Today most Bletchley Park Trust visitors miss the key experience of seeing the Colossus Rebuild and the Tunny machine in action and thereby miss out on key working exhibits representing the outstanding pinnacle of the World War Two code-breaking story.
“Negotiations with the Bletchley Park Trust to achieve a fair and equitable financial arrangement to give all Bletchley Park fee-paying visitors access to Colossus and Tunny have proved exceedingly difficult.
“The Bletchley Park Trust’s current action to erect gates and barriers between its own display area and Block H will almost certainly prove divisive.
“TNMOC wants to see the whole Bletchley Park site reach its full potential in honour of the men and women who worked at Bletchley Park during World War II. This can be achieved by ensuring that all stakeholders are properly consulted and represented in the revitalisation of the conservation area that constitutes the whole of Bletchley Park.
“The need for change, sensitively managed and involving all stakeholders, is essential to ensure the future of a vibrant Bletchley Park which will be inspiring for young people and future generations.”