The 40-odd academics believe that if the pounds 11m extension goes ahead, their time-honoured afternoons spent reading and taking tea in the Fellows' Garden would never be the same again. The "big block" would be "intrusive", would "overpower" the garden and obscure the view.
The Master of Peterhouse, Sir John Meurig Thomas, and the governing body have lodged protests against the plans for the northern extension, which is set back 1.5 metres from the wall which divides the two institutions. More than 3,300 dons and senior administrators will be balloted on the issue next month.
Professor Christopher Calladine, the senior fellow of Peterhouse, will be voicing his objections. "Everyone with a garden and a neighbour is likely to object to the neighbour's building coming right up to the wall, when it previously didn't," he said.
"At the moment, if we stand in the Fellows' Garden, we see the big block of the museum in the distance, about 60ft beyond the wall. The new proposed northern extension will bring the northern extremity of the museum right up to practically the wall. It will be a big block of building overshadowing our garden."
However, Professor Calladine insisted that Peterhouse's main objection was a "moral" one. The land on which the museum is built was originally sold to the university by Peterhouse in three stages. Building on the north side was "against the spirit" of the last sale in 1915. The availability of land to the south of the museum also meant there was an alternative site.
The extension would involve cutting into the northern wall of the building designed by George Basevi, a protege of Sir John Soane, in 1834, with a giant classical-style portico commanding its east-facing entrance.
David Watkin, an architectural historian and fellow of Peterhouse, said: "It is a Grade One listed building. It deserves to be respected, not mutilated."
Duncan Robinson, director of the Fitzwilliam Museum, is keen that the museum should provide the public with the services of a "late-20th century museum."
He believes that Peterhouse's objections are garden-based. "The first problem the college has is that they don't want to look at it," he said. "From there they are going on, quite naturally, to saying that extending a Grade One listed building is a very sensitive issue and we should not be adding to the original building."
Caroline Elam, editor of the Burlington Magazine, the monthly art history journal, and member of the Fitzwilliam syndicate, believes that even Basevi would have been in favour of the extension.
"Basevi himself was well aware that additions to north and to south of the Fitzwilliam might prove desirable, as his drawing of 29 June 1836 makes clear," she wrote to the University Vice-Chancellor.
She went on to put her case: "The proposed northern extension in its modified form is modest in scale and deliberately reticent in character ... The architect, John Miller, is particularly well-known for his sensitivity to the needs of historic buildings: his work at the Whitechapel Art Gallery not only won prizes, but, perhaps more importantly, continues to look good and function well."Reuse content