LONDON (Reuters) - Hours after the Manchester suicide bombing, British Prime Minister Theresa May stood on the steps of her official Downing Street residence and promised to give police the resources they needed to investigate the attack.

A soldier and police officer walk past the Houses of Parliament London, Britain May 24, 2017. REUTERS/Neil Hall

For police in the northern English city, her assurance given in London on Tuesday offered some hope and comfort after years of cost-saving cutbacks - many of them launched by May in 2012 when she was interior minister.

Some police say privately they believe security in the capital - 250 km (160 miles) to the south of Manchester - has been prioritized at the expense of other cities, where staff cuts have hit hard, career opportunities have been reduced and many officers fear for their jobs.

Graphic on police staffing levels: tmsnrt.rs/2qjwkiG

It is not clear whether the cutbacks - imposed as the government slashes spending across most departments to reduce its budget deficit - did anything to make Manchester more vulnerable to an attack like Monday night’s bombing after a concert by U.S. pop star Ariana Grande.

Nevertheless, they opened an old sore for some. “No one can tell what goes through the minds of these radicalized individuals, it’s so unpredictable and hard to police,” said a Manchester police officer, who spoke on condition of anonymity because he is not authorized to speak to the media.

“However, a reason could possibly be that the different level of security between London compared with Manchester played a role.”

The officer describes five years of attrition, seeing “fewer bobbies on the beat” - a reference to frontline police whose presence on British streets offers them insight into local affairs and sometimes snippets of intelligence brought by people who would not necessarily pick up the phone.

Greater Manchester Police declined to comment and the Greater Manchester Police Federation, the force’s de facto trade union, did not respond to a request for comment by the time of publication.

May, who became prime minister last year after Britain voted to leave the European Union, said on Tuesday the official threat level in Britain had been raised to its highest level, “critical”, meaning an attack could be imminent.

The army was drafted in, taking on guard duties at places including Queen Elizabeth’s London residence Buckingham Palace, Downing Street and parliament to free up police to concentrate on patrols and investigations. Some officers said they would face hours of overtime work to cover the additional demands.

Slideshow ( 3 images )

FORTRESS LONDON

Addressing those officers on Tuesday morning - just hours after 22-year-old Salman Abedi blew himself up in the foyer of the Manchester Arena, killing at least 22 people including children and teenagers - May promised to give them “all the resources they need to complete that task”.

It is a statement she has repeated since as the police and security services look into whether Abedi was part of a cell. The police have said they now believe it is “very clear” they are investigating a network.

London has been the focus of additional security since an attack in March when Khalid Masood plowed his car into people on Westminster Bridge leading to parliament, killing four before stabbing to death a policeman on guard at the building.

New barriers have been put outside Buckingham Palace and other high-profile sites. In parliament, armed police have become a more prominent fixture.

Some police officers outside London have long criticized what they see as the capital getting the lion’s share of funding and personnel - feeling less of the brunt of the cuts than forces in other cities and towns.

Since 2012, Greater Manchester Police has seen a steady decline in its workforce, with the steepest fall last year. London’s Metropolitan Police has also seen a contraction over that time but at a slower rate.

May, who as a former Home Secretary was an architect of some of the cuts, has often been the focus for criticism.

In 2012, thousands of police officers and supporters took to the streets to protest against the budget cuts of 20 percent in England and Wales, with May accused of everything from benefiting from privatizing some police functions to ignoring the plight of officers struggling with lower pay.

At the Police Federation conference that year, she was heckled when she told members: “So let’s stop pretending the police are being picked on. Every part of the public sector is having to take its share of the pain.”

One police officer wrote a letter detailing some of the widespread criticisms of a two-year pay freeze and removal of some terms felt by many: “Morale is certainly the lowest I have ever known,” the officer, who was not named, wrote in an email to the Greater Manchester Police Federation.

“I personally stand to lose a significant amount of money with the current changes. Money that I have worked hard (for) and in my eyes earned. I do know I am going to have to look at a second job to supplement the money lost.”

It was a similar message that the police gave interior minister Amber Rudd earlier this month at the annual conference of the Police Federation of England and Wales.

“We are a service that wants to deliver what the public want, when they want it and how they want it – 24 hours a day, 365 days a year. But this is getting impossible,” chairman Steve White said.

“It is a crisis that we don’t have enough police officers to deal with the demands placed upon the service – and that should be very worrying for government, whose primary responsibility is the safety and security of its citizens.”

And that will drive most to work overtime to get to the bottom of what made Abedi bomb concert-goers as young as eight and whether he was helped by others.

“But at the end of the day, the radicalization of vulnerable people is hard to police against,” the officer said.