With a shout of "Na wrewgh tava agan ordir!" the Grand Bard of Gorsedh Kernow expressed the anxieties of all those fighting government moves to tamper with Cornwall's ancient border.

Following news that the Boundary Commission is threatening to merge a chunk of South East Cornwall with a Plymouth parliamentary constituency, the leader of the Cornish cultural organisation took the opportunity of its annual ceremony to mobilise those opposed to the measure.

The proposal, which is being overseen by Deputy Prime Minister Nick Clegg, was the most pressing issue being discussed at the gathering of bards in St Ives on Saturday.

After delivering his customary welcome to fellow bards and guests, as well as townsfolk and tourists, Mick Paynter rounded on the Government in the most overtly political speech delivered by a Grand Bard in recent years.

"This is a threat to our territorial integrity," he said. "It is a threat buried in the Coalition's plans for electoral reform. Lest there be any doubt as to the meaning of 'one and all' we should show it together by saying, loudly, that the Tamar has been our border for more than a thousand years. It is a historical border, it is a cultural border, it is a linguistic border, and it is recognised as such by Europe. The Tamar is our national border. Na wrewgh tava agan ordir! Hands off our border! Gesewgh Kernow dhe vos Kernow! Let Cornwall be Cornwall!"

The rallying cry, which Mr Paynter hopes will encourage everyone who cares about Cornwall's physical integrity to oppose the Coalition's plans, was greeted by loud cheers from bards and onlookers.

The Gorsedd ceremony, which is held at a different location every September and conducted through- out in the Cornish language, is intended to be a visible declaration of loyalty to Cornwall. This year around 300 blue-robed bards processed from St Ives Guildhall across the seafront to The Island.

Bright sunshine, views of surfers and sunbathers on the beach below, and the natural stadium of the promontory's high rocky outcrop, made The Island a perfect setting for the event.

With the bards arranged in a circle, the ceremony followed a traditional pattern. After a series of opening blasts from the horner and the collective cry of Cres! (Peace!) to all corners of the nation, Grand Bard Mick Paynter spoke of his pride at leading the event in his home town. Mr Paynter, who is descended from a famous family of boatbuilders, said: "The bards of Cornwall's Gorsedh are happy to be here in St Ives, which is one of the jewels of Kernow. It has a fine, long and interesting history and it's a heavy thing for me to be here as Grand Bard because I was born, bred and brought up here in this place.

"St Ives is important to the Gorsedh because the modern Cornish revival began here. Ninety years ago Henry Jenner and Robert Morton Nance created the first branch of the Old Cornwall Society to gather up the fragments of our culture so that nothing be lost. From that day it was a quick and constant progress for our movement until in 1928 Pedrog the Arch-Druid of Wales inaugurated Gorsedh Kernow at Boscawen Un with Jenner as the first Grand Bard and Nance his deputy. The rest is history."

Flower dancers delighted the crowds and the "fruits of the earth" were presented to the Grand Bard by Lady of Cornwall and surfing champion Tassy Swallow, from St Ives. Bards sang Bro Goth Agan Tasow (Old Land Of Our Fathers) and Hayl Dh-agan Mammvro (Hail To The Homeland), before pledging allegiance to Cornwall through the symbolic communal touching of the sword. Bards who died in the past year were remembered and awards presented to competition winners and others. This year, for the first time, a new ceremony was added. The Joining of the Sword saw representatives of the Welsh and Breton gorsedhs express friendship and peace as two sides of a blade were united.

Sixteen new bards were welcomed into the circle on Saturday, having been recognised for their exceptional contribution to a specific area of Cornish life. Among them was Alan Pope, who has worked tirelessly for youth brass bands, film-maker Denzil Monk, maritime historian John McWilliams, fisherman James Muirhead, and Hilary Keam, a champion of Cornish dialect.

The full list of new Bards is: Leslie Cleave of Wadebridge, for services to Cornish Wrestling; Mary-Ruth Collins of Mabe Burnthouse, by examination in the Cornish Language and continuing work for Cornwall; Shelagh Garrard of Constantine, by examination in the Cornish Language and continuing work for Cornwall; Colin Gregory of Truro, for services for Cornwall through the media; Peter Harvey of Camborne, by examination in the Cornish Language and continuing work for Cornwall; Raël Harvey of Camborne, by examination in the Cornish Language and continuing work for Cornwall; Hilary Keam of Probus, for services to Cornish dialect; Kathryn Matthews of Heamoor, for encouragement of Cornish culture and language with young people; John McWilliams of St Ives, for services to Cornish maritime history; Denzil Monk of Penzance, for services to Cornish film making; James Muirhead of The Lizard, for services to Cornish fishermen; Penny Norman of Rosudgeon, by examination in the Cornish Language and continuing work for Cornwall; Alan Pope of Illogan, for services to encouragement of youth in brass bands; William Roberts of St Austell, for services to Cornish wrestling; Jeremy Rogers of Sandhurst, for services to Cornwall in the wider Celtic world; Trevor Smitheram of Mawgan, by examination in the Cornish language and continuing work for Cornwall.

The ceremony was followed by another procession through the town and an evening concert featuring local choirs, bands and entertainers, organised by Keith and Clarinda Truscott.

The 2011 Gorsedh is due to be held in Helston.