There will be a consultation paper later this year on whether legislation is needed to ensure that reservists do not face discrimination in the workplace, and potentially greater compensation for their employers, who have to find replacements for them when they are called up.

As the British Army is undergoing an intensive review, leading to the scrapping and merging of battalions and mass redundancies, Defence Secretary Philip Hammond has made it clear that its future depends on integrating regulars and reserves, with enormous numbers having to be recruited over the next three years.

Mr Hammond said: “Delivering this step change in the size and role of the reserves will require a change in the relationship between defence, the employer and the reservist.

“Many employers already give excellent support to reservists, for which, we and the nation are grateful.  But we need a new framework of partnership, with public and private sector employers that gives us the confidence that trained reservist manpower will be available when it is really needed.”

However, a Federation of Small Businesses spokesman said: “It shouldn’t be forgotten that small firms are operating in the same tough economic conditions that have compelled ministers to make big cuts to the regular Army.”

“Businesses would be in a much better position to cater for the proposed doubling of the Territorial Army if the government had at least said how it would encourage and compensate firms for complying.”

And former head of the Army Lord Dannatt said that “employers have got to be willing,” which is “a big ask”.

Current head of the Army General Sir Peter Wall said that the laws protecting reservists and the companies they work for will have to be revisited, as “the full integration of the reserves will be a central requirement if levels of capability are to be met.”

“We are relying on greater capability from the reserves,” General Wall added and said that there was a possibility of “significant changes to terms and conditions”. While Mr Hammond said: “If it requires new laws, we will legislate.”