IT was the moment the Forth bid farewell to the Clyde.

On an early, crisp February afternoon the Royal Navy’s newest ship slipped under the Erskine Bridge and sailed past Dumbarton Castle. She may never be back.

The offshore patrol vessel, soon to be “HMS” Forth, was on her way to her official new home, Portsmouth. But her journey is only just beginning. Once commissioned, the Forth is to take up the furthest flung post of the British navy: guarding the Falkland Islands. And, that involves the craft, not quite 300ft long, crossing 8,000 miles of ocean.

There the Forth will replace HMS Clyde, which has spent a decade as Britain’s deterrent against an Argentinian invasion after taking over from HMS Dumbarton Castle.

Such a long and distant deployment means Jamie Dorans who helped build the ship is unlikely to see his handywork again.

“I haven’t exactly shed a tear,” the 19-year-old apprentice says as watches sailors prepare to pull away from BAE Systems’ Scotstoun yard. “But it’ll be sad to see her go. I don’t think we’ll see her again.” Mr Dorans, a sheet metal worker, made and fitted cabinets and ventilations systems for the Forth’s galley, the heart of the ship. “Everything has got to be just right,” he adds, beaming with pride. “The last thing you want in the galley is a fire. We have got to protect our lads when they are at sea.”

The Forth lay low with the tide at the dock side at Scotstoun before her last departure. She is the first of five new offshore patrol vessels, small ships designed to be versatile, to fight pirate or tackle smuggling.

Just upstream, at BAE Systems at Govan, two others of her class, Medway and Trent, are coming down the production line, their bows poking out of the yard’s big shed.

The Forth was “launched” back in 2016. This is no longer the occasion it was once was as so-called dynamic launches – when a ship is allowed to slide in to the narrow Clyde – ended years ago.

Since then shipbuilders like Mr Dorans have been fitting her out before she underwent sea trials.

Now her first crew is taking her over.

Commander Bob Laverty, of the Royal Navy, will be taking her down to Portsmouth and then to the South Atlantic to replace HMS Clyde, which he used to command.

Mr Laverty, 46, is pleased with his new charge. Its a “big change” from HMS Clyde, he says, which spent 10 years in the South Atlantic, bar maintenance periods in South Africa, and which, despite its name, has no association with Scotland.

The Forth, Mr Laverty explains, is “pretty comfy”. She has to be: she can spend 320 days at sea and cover 5,500 miles on a single “tank” of fuel. She has a helipad at her rear, a gun on her foredeck and a superstructure bristling with high tech radar and weapons systems its makers do not want to discuss.

Mr Laverty can fit a crew of 58 but the Forth also has a room full of bunks so she can carry another 50 soldiers. He is hoping and expecting the ship, which has still to encounter any heavy seas in its trials, will be a good “seakeeper”.

He added: “Some of us will know the feeling of driving a brand new car out of the showroom for the very first time – and taking ownership of a brand new ship evokes similar emotions.

“It is truly a great privilege not only to take a new ship out but also a well formed and trained crew. I feel a great sense of pride and excitement to have the opportunity to put the ship and her company through its paces.”

Britain has been beefing up its defences of the Falklands. Argentina continues to press its territorial claim to Las Malvinas and other Latin American countries have refused to offer port services to HMS Clyde.

The UK announced a new ground-to-air missile defence for the Falklands and the Forth will form part of an army, RAF and navy force of 1,300 which accounts for roughly a third of of the islands’ population.

Last year the first steel was cut for new Type-26 frigates – vessels three times the size of the Forth.

The first will carry another familiar Scottish name: HMS Glasgow.