Shifting Royal Marines based in Scotland to the Westcountry to unite all three commando units in the region did not "represent value for money", the Government has said.
Defence Secretary Philip Hammond last week announced 45 Commando, currently based in Arbroath, would stay north of the border for the "foreseeable future". Previously, the Ministry of Defence had said 45 Commando would be moved to the South West, closer to 40 Commando in Taunton and 42 Commando in Plymouth.
Explaining the reasons for the U-turn in the House of Lords, ministers said it did not make economic sense "at this stage". This echoed the stance taken by Mr Hammond, who stopped short of ruling out the Scottish-based commandos making the move at some point in the future.
The Secretary of State told MPs at Westminster last week that 45 Commando would remain in Arbroath for "the foreseeable future".
It had been planned for around 800 Marines and 200 support staff to move to the region in 2016. One option raised as part of a potential consolidation of naval training sites was relocating 45 Commando to HMS Raleigh in Torpoint, Cornwall.
Defence Minister Lord Astor was asked about the decision to keep 45 Commando in Scotland by former Tavistock MP and Royal Marine Lord John Burnett.
He replied: "We investigated the feasibility of the move to the South West, but that option did not, at this stage, represent value for money and Arbroath is not needed for Army basing in Scotland.
"It is my understanding that 45 Commando is very happy with this decision."
The change of heart on re-locating 45 Commando for the time being will inevitably fuel speculation that the reason is more political, coming ahead of the upcoming referendum on Scottish independence in 2014.
But informed observers also believe it could be linked to the complex logistics of the move to the South West.
Naval training is currently carried out at both HMS Raleigh, for ratings, and the Britannia Royal Naval College at Dartmouth, for officers.
Bringing this together on a single site is set to cost time and significant amounts of money, as well as adapting facilities for the arrival of the Royal Marines.
Devonport-based ships were scrapped and city sailors' jobs lost as part of the Government's Strategic Defence and Security Review (SDSR) in 2011.
It was hoped the impact of the SDSR would be offset by the region gaining the Scottish-based Marines.