Delivering a safe and secure Olympics with the emphasis firmly on the athletes’ sporting achievements was a major objective for many diverse agencies.

The crew of HMS Ocean were among those who played a very visible and tangible part in ensuring the London 2012 Olympic and Paralympic Games went without a hitch.

She took part in a 10-day exercise to prepare for the task of delivering an umbrella of security around the capital and the various Olympic venues.

When she returned on July 13 to play her part in the Olympics she became an almost permanent fixture on the River Thames moored at Greenwich.

She left almost two months later, on September 12, just days after the end of the Paralympics. By then she had hosted more than 11,000 visitors from across London and further afield, youth organisations, several members of the Royal Family and even the Prime Minister.

Having been on board the ship on the day the Olympics opened to the world with a spectacular ceremony I couldn’t resist the chance to sail with her as she began her journey out of London.

The difference in the ship was apparent as soon as I set foot on board - the vehicle deck looked like someone’s living room once its been cleared of furniture and items packed ready for shipment.

The flight deck, used by 10 Army Air Corps and Royal Navy Lynx helicopters, was empty bar the tied down crates and trucks. Their absence served to highlight the sheer size of the deck.

The atmosphere on board the vessel was akin to someone about to move house as the flight deck was empty of aircraft, making it look huge, as was the aircraft hangar below. Another deck which usually houses vehicles contained crates and other large items tied down. Although the ship was headed for Amsterdam she will soon be in Plymouth for a refit.

The vessel, which has buzzed with activity and lost of troops in July, also felt as though it was running on a skeleton staff as there were much fewer people on board.

Another huge difference was the Ship’s Control Centre which was full of displays as its crew monitored the ship’s essential systems as she prepared to sail off. While moored at Greenwich, there were only two people required at the centre, now there will 36 of them a day, with six at a time, around the clock.

Chief Petty Officer Stephen Perry said: “The ship is like a small town so everything that you take for granted in your house - the freshwater, heating, lighting, sewage works and cooking - it all has to be done in house and the Ship’s Control Centre monitors everything.”

The ship also has four, it must be said very noisy, diesel generators that act like a boiler in a house, keeping all its vital systems running.

The ship’s role in providing security was two-fold - helicopters monitoring the air and the soldiers providing security at Olympic venues.

Lieutenany Colonel Neil Wraith, a Royal Marine Commando, is normally in charge of a Royal Marine assault squadron but was overseeing 750 servicemen and women in Greenwich in his role as Venue Security Military representative for more than two months.

He said: “All the security force has really enjoyed the experience during the Games and the opportunity to deal with up to 50,000 people on a daily basis was very exciting, rewarding and challenging. Its not completely alien to us because we are used to engaging with the public.”

He said although they expected to play a part in the security of the Olympics, what was nice was the atmosphere and the way the members of the public engaged with soldiers and sailors. So much so that the security aspect became a part of the overall Olympics experience rather than a hassle.

He said: “The thing is that the troops had a fantastic opportunity to be a part of the event. In the course of every day the majority of them were interacting with athletes.”

Now, as the ship prepared to sail, Lt Col Wraith said: “There is a tangible sense of relief that the focus was on the sport rather than security.”

Lieutenant Commander Scooby Plenty was Flyco on the ship which meant he was in charge of flying operations by the ten Lynx helicopters, five manned by Army Air Corps crews and five by flown by the Royal Navy. He too felt the security operation had been a success. He paid tribute to the civilian agencies whose close cooperation contributed to the success of the security operation. He said: “The key message is that it was never a military operation. It was always a civilian operation by other agencies that we would assist. For it to be successful, if you like, we had to do the minimum.”

As we waited for the ship to slip from its buoys, Lt Cdr Plenty said the entire crew on the ship felt honoured to have been part of the security operation. For many it was a unique chance to be deployed to London and specifically at Greenwich with its long naval history.

After weeks of guarding the skies over London during the Olympic and Paralympic Games, HMS Ocean and her 400-strong crew left Greenwich in a low key departure.

There was no fanfare or fuss onboard the helicopter ship which quietly sailed down the Thames with the help of four tugs and a police escort to help her navigate the narrow channel.

Crowds of people and groups of schoolchildren lined the sides of the Thames as she sailed gracefully towards the sea. Sailors stood in groups and waived as they took a last look at the view.

Many were looking forward to spending time with families and loved ones but that happiness was tinged with a little sadness that a unique experience was at an end.

There was an almost sombre atmosphere as the ship began its almost silent journey down the River, past the Cutty Sark, O2, Canary Wharf and the Thames Barrier.

For a ship of its size, 20,700 tonnes, she seemed to move effortlessly, almost gliding through the water.

Tugs were still with us well after the Thames Barrier - out of courtesy and the police escort keeping other vessels and shipping away from us by 50 metres

And before I knew it we were fast approaching Gravesend where we left the ship in a landing craft, giving us yet another taste of life for the troops.