A police force that handed over the bulk of its back-office functions to the private sector now spends the lowest amount per head of population on policing in England and Wales, a report has said.
In the first year of its deal with private security firm G4S, Lincolnshire Police has slashed spending by nearly a fifth or £5 million per year - equal to the cost of 125 police officers.
Lincolnshire police and crime commissioner (PCC) Alan Hardwick claims the national purse could save £1 billion if the other 42 police forces in England and Wales followed suit.
The contract, which saw 18 operational and organisational support areas and 585 staff transferred to G4S Policing Support Services, started on April 1 last year and is due to last for 10 years.
Independent PCC Mr Hardwick said: "Tomorrow's Spending Review is likely to outline billions of pounds of additional cuts to public spending. This is on top of sizeable reductions already made. For police forces, whose budgets are already nearly 20% leaner than in 2010, the challenge - to improve quality while finding savings - is about to get bigger."
Among the departments transferred to private hands were the force control room, firearms licensing and custody.
Mr Hardwick, who was heavily criticised by a High Court judge earlier this year for wrongfully suspending Lincolnshire's chief constable in a decision that was ultimately reversed, said the force had slashed crime by more than 14% in the first year of the contract.
The police force had expected to make savings of £3.6 million in the first year but exceeded this by £1.6 million.
A four-month backlog of files for processing firearms licences has been cleared while the 999 call response rate has improved to an average of more than 93% of calls answered within 10 seconds, up from an average of 89% in 2011/12.
The full term of the agreement is expected to see Lincolnshire Police make £36 million in savings.