The public are growing increasingly wary of reporting crime, according to a member of HM Inspectorate of Constabulary.
Matt Parr told ITV Anglia people have become aware that so-called 'trivial crime' is unlikely to get investigated.
He blamed the trend on cuts to police forces over the past decade, as well as an increase in the volume of crime.
Matt Parr, from HM Inspectorate of Constabulary, spoke to ITV Anglia's Rob Setchell
Mr Parr said: "Policing’s been under pressure for a number of years now, the austerity, the budget cuts are well known and thankfully they're now being reversed.
"Also the complexity of crime has got worse, the volume of crime has got worse."
The announcement comes on the day that Bedfordshire and Cambridgeshire Police received their official reports from HM Inspectorate of Constabulary.
Nevertheless, Mr Parr said pressures on forces nationwide have resulted in the public losing faith in securing a prosecution.
He added: "There is an increasing number of people who are not supporting the prosecution, so they don’t report crime or they do but then they lose faith and pull out of the prosecution all together.
But he warned it would take some time for their impact to be felt.
He said: "The 20,00 uplift is good news, but it won’t turn things round overnight, these new officers have got to be recruited and trained."