All that will happen....
The UK gov depts find it impossible to recruit and retain good permanent ICT and Security people. If the UK gov departments stop hiring so many independent contractors, they will end up outsourcing to big business and big business will hire the contractors, costing the government extra. The UK gov has to do one of three things:
1. Offer salaries in excess of those available in Industry to stimulate recruitment & retention
2. Hire independent contractors to fill key posts and help them manage the big business outsourcers
3. Streamline security vetting processes to enable faster recruitment
The government will never do 1 or 3, so are stuck with 2.
If the government really wants to save money they should make a lot of civil servants redundant where they dont perform, the civil service is far too protectionist of jobs for the unproductive and breeds laziness, they'll never do it though, because of the votes carried by the unions. The reason independent contractors stay in government is because they work hard, you dont need a reason to terminate a contractor, if he or she doesn't deliver, you serve them notice.
If you have a waste of space civil servant, it's near impossible to get rid of them.