Another sign of UK forces overstretch ?

The sad death of a UK contractor in Afghanistan highlights other issues aside from the security situation in Afghanistan, most notably why is the defence of UK government staff in the hands of a private security firm and not being organised by the UK military ?

Contractors in places like Iraq and Afghanistan are often accused of working at the very edges of the law, indeed often going beyond it in their possession and use of weapons, and the UK ought to be leading by example here.

I might be putting two and two together and getting 13, but isn't this a sign of UK forces yet again being overstretched to the extent we pay mercenaries to defend UK government staff abroad ?