131 Commando Squadron Royal Engineers is an Army Reserve unit and part of 24 Commando Regiment Royal Engineers. It provides engineering support to UK Commando Force. (3 Cdo Bde RM) and is the largest Army Reserve Commando unit. The squadron has deployed worldwide to provide combat engineer support to the UKCF, often deploying in small sub-units. 131 was first raised in 1947 as an airborne engineer regiment, and reached a strength of over 1,000 trained parachute engineers by the early 1960s. Between 1 April 1978 and 1 October 2015, the unit was an independent Commando squadron under operational command of HQ 3 Cdo Bde RM. On 2 October 2015, it formally became the third squadron of 24 Commando Engineer Regiment.

With the reformation of the Territorial Army (TA) in 1947, the unit was raised as 131 Airborne Engineer Regiment in support of 16th Airborne Division. The division, taking its number from the wartime 1st and 6th Airborne Divisions, was commanded at first by Major-General Roy Urquhart (who had led 1st Airborne Division at Arnhem in 1944) and consisted of three TA parachute brigades (44, 45 and 46 Parachute Brigades), each of three parachute battalions.

With all volunteers going through 'P Company' to gain their Maroon Berets and earning their Parachute Wings at RAF Abingdon, the regiment provided a squadron of parachute engineers to support each brigade: 299 Airborne Field Squadron in Hull; 300 Airborne Field Squadron in Liverpool, later Glasgow; and 301 Airborne Field Squadron in Croydon. The regimental headquarters was in Pont Street in Knightsbridge, with 302 Airborne Field Park Squadron based in Hendon. Manning a regiment of this size presented no problems, with many recently demobilised World War II soldiers, including many former paratroopers, willing to join the regiment. Indeed, it was one of the fullest of all units within the brigade. Experienced leadership was also readily available. 299 Squadron was raised by Major George Widdowson, previously of the Green Howards, who had fought at Arnhem as second-in-command of the decimated 10th Battalion, Parachute Regiment, whilst at Surrey-based 301 Squadron Major Beverley Holloway became Officer Commanding and later regimental second-in-command. His World War II service included parachuting into Normandy on D Day as a troop commander with 3rd Parachute Squadron RE.

Territorial Army reorganisations took place in 1956, with 16 Airborne Division being disbanded and replaced by a single TA parachute brigade, 44 Independent Parachute Brigade Group. 131 Regiment was sufficiently well established to ensure that it was retained in size but redesignated as 131 Parachute Engineer Regiment, with all squadron titles replacing the term "Airborne" with "Parachute". RHQ moved half a mile to the Duke of York's Headquarters in the King's Road, Chelsea, co-located with Brigade Headquarters. Troop locations evolved through the 1950s too, with 301 Squadron moving to Guildford and gaining a Birmingham based troop as a result of the demise of 18th Battalion The Parachute Regiment. The Liverpool-based troop also went on to become part of 299 Squadron, whilst 300 Squadron, gained troops in Edinburgh and Falkirk to become wholly Scottish. One final change saw 302 Squadron move from Hendon to nearby Kingsbury, with its Luton-based Plant Troop also relocating to Kingsbury, in 1959.

In the early 1960s, 131 fielded over 1,000 trained parachute engineers and was believed to have the largest number of men earning their annual bounty in the whole of the Territorial Army. Many of the unit's members were also members of the Emergency Reserve, giving them a higher call-out obligation. Basic training was only beginning to be introduced because, up until this time, almost all unit members were either ex-regulars, ex-WW2 volunteers or ex-National Servicemen. Throughout this period of the regiment's existence, squadron-sized detachments served their annual camps in many overseas theatres, carrying out close support and construction engineer tasks as well as parachuting with United States, Canadian, French and Italian forces. A major regimental event during the 1960s was Exercise Sea Splash, during which its soldiers would parachute into the harbour in St Peter Port in Guernsey, awaited by a fleet of small boats and cheering islanders. 131's first Honorary Colonel, Lieutenant General Sir Philip Neame VC, KBE, CB, DSO, had initiated the regiment's involvement with the island when he served as its governor after the war, and the parachute foray was always treated as a celebration of the liberation from German control in 1945.

In 1965, the bulk of the regiment carried out its Annual Camp in Aden Protectorate and in 1966 elements of the regiment deployed to the country again. During the 1965 deployment ('Ex Jockey Club') on the night of 12 April, 300 Parachute Squadron was attacked by guerrillas whilst working with 24 Field Squadron on the construction of the Dhala Road at Al-Milah near the Yemen frontier. Squadron Sergeant Major John Lonergan of 300 Squadron and Sergeant Atfield, the pay sergeant of 24 Field Squadron, were both killed during the action and are buried at the Ma-Allah Cemetery, now within the Republic of Yemen. Major Clive Samuel, the Regimental Medical Officer, was awarded the MBE for gallantry after he risked his life to attend to those wounded and rescued two badly wounded men caught out in the open. The incident became known as the Battle of Dhala. 131 Commando Squadron Royal Engineers's base is named Lonergan Lines in honour of SSM Lonergan.

The second major post-war reorganisation of the TA in 1967 saw the regiment reduced to a single independent squadron of 250 personnel on 1 April 1967. 131 Independent Parachute Squadron Royal Engineers (Volunteers) maintained its role in support of the three parachute battalions of 44 Parachute Brigade (Volunteers). Squadron Headquarters and the Support Troop was based in Kingsbury in London, with Troops in Birmingham, Hull and Grangemouth. Troops took the names of the Squadrons they had replaced, with 299 Troop in Hull, 300 Troop in Grangemouth, 301 Troop in Birmingham and 302 Troop (Support Troop) in Kingsbury.

The three field troops each continued to support a TA parachute battalion, with 299 Troop linked to the 4th (Volunteer) Battalion The Parachute Regiment, 300 Troop to the 15th (Scottish Volunteer) Battalion and 301 Troop to the 10th (Volunteer) Battalion. Overseas travel, with associated opportunities for engineer support, construction and parachuting continued. At times, troops carried out annual camps in direct support of their battalions, such as 299 Troop's 1972 camp with 4 Para in Jamaica, whilst on other occasions the squadron exercised as a whole. In 1973, the squadron undertook Exercise Sacristan in the United Arab Emirates, which saw 180 members of the squadron deploy for between two and six weeks, carrying out a variety of construction tasks and desert training exercises. Close ties with 9 Independent Parachute Squadron RE, then based at Church Crookham, also continued throughout the period.