Suffolk Constabulary has achieved government spending cuts without radically reforming how it operates, the official policing watchdog has said.

In a report published this month, HM Inspectorate of Constabulary said the force has 'successfully reduced' its spending by £18.8million from 2011/12 to 2014/15 and raised the proportion of frontline roles from 91 per cent in 2010 to 94 per cent in 2015.

But the report warned that the force's current workforce model, which meets financial and organisational challenges, will become 'unsustainable' ahead of further planned cutbacks.

The report, which overall ranked the force as good, the second best out of four rankings, said: 'The constabulary is continuing to improve its understanding of the current demand for policing services across the county.

'However, it needs to do more to gain a sufficiently comprehensive picture of current and likely future demand, so that it can plan effectively.'

The force's partnership with Norfolk police was described as 'mature and successful', while it achieved a balanced budget in 2014/15 and has a planned balanced budget for 2015/16.

The report added: 'The approach to reducing spending has been managed robustly and resulted in savings accruing ahead of time allowing the constabulary to build up financial reserves.'

Temporary Chief Constable Gareth Wilson, of Suffolk Constabulary, said: 'I am extremely pleased with our positive grading and am confident that plans are already in place to respond to those areas

where inspectors felt we could improve.

'Suffolk is an extremely low cost force. This is highlighted in the report which shows us once again as costing considerably less per head of population than the average in England and Wales. This makes the challenge ahead even more acute, as we look to deliver savings from a budget which is largely spent on people. Along with the inspectors, we recognised that at the time of the inspection in April there was a clear need to enhance our understanding of the demand we face.

'Since then, demand analysis, coupled with extensive internal and external consultatio,n has driven the development of our plans for redesign.'

Suffolk's police and crime commissioner Tim Passmore (pictured) said: 'The report confirms what we already know – we need to change the way we deliver policing services to meet future demands with a reduced budget.'