GETTY More than 27,000 of the UK's full-time military personnel were not classed as 'medically deployable'

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Lord (David) Richards, who was chief of defence staff from 2010-13, said the proportion unable to be fully deployed on operations was far worse than he thought and described further cuts as a “serious mistake”. With Britain leaving the EU and seeking to extend its global influence, he said the Government should be investing in the Armed Forces as part of “a post-Brexit grand strategy”. The general made his comments after official figures showed that of the UK’s 137,280 full-time military personnel, more than 27,000, around 20 per cent, were not classed as “medically fully deployable”. He said it needed to be “factored in” to any future decisions on the size of the military, which was already too small.

GETTY Gavin Williamson said the Government was committed to maintaining the overall size of the Army

There’s always a proportion not deployable on operations, usually around 10 per cent. Actually the figure is nearer 20 per cent Lord David Richards

Of those downgraded, the figures for October 2017 show 13,223 were “medically not deployable”, while a further 13,989 were “medically limited deployable”, due to a medical condition, temporary injury or illness. Amid threats from Russia and North Korea, there has been speculation about possible cuts to the military to relieve pressure on the defence budget. Defence Secretary Gavin Williamson said last week the Government was committed to maintaining the overall size of the Armed Forces. Lord Richards said: “There’s always a proportion not deployable on operations, usually around 10 per cent. Actually the figure is nearer 20 per cent. It’s only now we realise the situation is worse even than we had feared and the Armed Forces and our political leaders must factor that into their strategy.