A call has been made to protect Southwold's 'unique character' as groups joined forces to oppose plans by a national chain to open a new coffee shop in the town.

The Southwold and Reydon Society and the Southwold Chamber of Trade vowed to fight proposals by Costa Coffee to open a new branch at 70, High Street – formerly Fanny & Franks' clothes shop.

In a joint letter sent to their members and local councils, the two organisations said the national chain posed 'a very real threat to the unique character of Southwold' and the future of its independent traders.

Their view has been backed by the mayor of Southwold who said the town council would not be 'bullied' into backing the plans.

After long-standing rumours that Costa Coffee was looking to open in Southwold, the company has now applied to Waveney District Council for 'a change of use' to allow customers to eat on the premises.

In the joint letter, Guy Mitchell, chairman of the chamber of trade, and Michael Rowan-Robinson, chairman of the Southwold and Reydon Society, state: '[We] will be opposing this application which we believe poses a very real threat to the unique character of Southwold High Street and to the viability of other local shops.

'Southwold already has 20 outlets in the town centre where coffee and/or food can be bought. They represent almost a quarter of the total number of ground-floor business premises in the town.

'There are a further 11 outlets outside the town centre, notably along the promenade and on the pier. Why, therefore, do we need another one?'

The letter – sent to Waveney council, Southwold Town Council and displayed on public notice boards – adds: 'The National Planning Policy Framework which local authorities must follow says any new development or change of use should 'reflect the individuality of town centres and improve diversity and vitality'.

'The arrival of a Costa Coffee shop would have completely the opposite effect.

'The appearance of yet another national brand – to add to recent arrivals Tesco, WH Smith and Aubin & Wills – can only detract from Southwold's individuality.

'We believe the application from Costa Coffee represents a watershed in the development of the town which, if unchallenged, could result in irreversible changes.'

Costa Coffee has 1,300 outlets in the UK.

It is run by Whitbread, which also owns budget-hotel chain Premier Inn and restaurants Beefeater Grill, Brewers Fayre, Table Table and Taybarns.

The mayor of Southwold, John Windell, said the town council would not be influenced by its success in other parts of the UK.

He said: 'An application has been put in for change of use, but most of the application is legal papers stating the reasons why we cannot recommend the application for refusal. I can say with authority that we are not going to be bullied by these people.

He added: 'I am cheered by the news that the Southwold Chamber of Trade and the Southwold and Reydon Society have come together to oppose this – it helps to show a united front.'

The EDP approached Costa Coffee and its agent, Savills, but no one was available for comment.