The under-strength and top-heavy Territorial Army has one officer for every four fully-trained soldiers on its books, The Herald can reveal.

The 21,069 part-timers, scattered from the Western Isles to Weymouth, are led by 10 brigadiers, 90 colonels, 340 lieutenant-colonels, 1670 majors, 1890 captains, and 1150 lieutenants, according to Ministry of Defence figures.

The details have emerged on the eve of the announcement of a major restructuring designed to make the reserve forces leaner and readier to deploy on demand in support of overstretched regular units.

Platoons or troops of about 30 men are normally led by second-lieutenants. Companies or squadrons of 100 are commanded by majors, and battalions of between 500 and 600 by lieutenant-colonels. Captains are usually second-in-command of companies or in battalion administrative roles, while colonels and brigadiers are staff officers at higher headquarters. If every senior rank in the TA was in charge of the unit his status indicated, there would be a minimum of between 117,000 and 167,000 reservists and they would far outnumber the regular army's current 98,000 trained soldiers.

One TA veteran told The Herald: "Most of us old-timers joined up to act as a formed reserve against a Soviet invasion of Western Europe. We would have deployed to Germany as complete units alongside our mates in the event of war.

"Now we're a cheap option to plug frontline gaps in the regulars in Afghanistan and Iraq and we deploy as individual replacements or in small groups, but never as entire battalions and seldom as anything even as big as a rifle company."

Sources say the MoD is now seeking to create a reserve force of about 15,000 who could be deployed as needed on six-month combat tours.

TA soldiers can currently escape compulsory mobilisation on the grounds of family or civilian career pressures.