The Army’s top brass had a huge row with Civil Service mandarins to stop them cutting the number of infantry battalions by a quarter, The Times can disclose.

During the restructuring of the service in 2004, which was ordered by General Sir Mike Jackson, then Chief of the General Staff, General Jackson himself fought to maintain an infantry force of 36 battalions - down from the existing 40.

He then fought with Sir Kevin Teb-bit, the Permanent Secretary of the Ministry of Defence, now retired,over an Army plan to transfer the 1st Battalion The Parachute Regiment to a new force providing support for the SAS and the Special Boat Service (SBS). The Times has learnt that General Jackson insisted that the SAS and SBS urgently needed back-up to help them in covert operations in Iraq and Afghanistan. The MoD mandarins saw this proposal as a ploy to save one battalion and worked out that the new role for 1 Para would add millions to the already-strained defence budget.

However, General Jackson won the argument after he and his senior army colleagues persuaded Geoff Hoon, then Defence Secretary, that the new role for 1 Para was vital. Mr Hoon had himself voiced the importance of special forces operations and indicated the need to enlarge the SAS and SBS.

It was later announced that 1 Para was to be formed into the Special Forces Support Group. This new unit has been involved in many of the recent covert missions in Iraq and Afghanistan.

General Jackson is likely to make some reference to his row with civil servants in his autobiography, Soldier, which is published this week.

The general, who retired in August last year, came in for considerable criticism over his plan, announced in December 2004, to form larger regiments, each with at least two battalions, and some with as many as five. The strongest attacks came from retired officers of the Scottish regiments after it was announced that six regiments were to be merged into a five-battalion formation to be called the Royal Regiment of Scotland.

The restructuring followed the decision by the executive committee of the Army board, headed by General Jackson, to end the traditional way in which battalions were given new roles and locations every two or three years. Known as the “arms plot”, General Jackson considered it outdated and the cause of needless disruption for soldiers and their families.

His decision to scrap this system was made possible by the peace deal in Northern Ireland, which cut troop numbers from 11,000 to about 5,000. Senior civil servants at the MoD argued that this withdrawal meant that the number of infantry battalions could be reduced from 40 to 30, but General Jackson and his board successfully argued for 36.

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