Staff staged a series of walkouts in protest at the regrading

Civilian staff staged a series of walkouts after hundreds faced losing up to �8,000 a year in a pay review.

The force backed down and promised an internal investigation, but Deputy Chief Constable Nigel Arnold has now called in the London force.

The Met will investigate whether any police officers "acted inappropriately" during the regrading of 2,400 staff.

Lessons learned

Devon and Cornwall Police said in a statement: "In response to allegations of possible misconduct during the recent Job Evaluation process, the Devon and Cornwall Constabulary has asked the Metropolitan Police to conduct an inquiry.

"It would be inappropriate to make any further comment whilst this inquiry is being carried out."

Jill Owen, former chair of the police authority, which called for the internal inquiry into the regrading, said she was "surprised" at the new investigation.

"There has got to be a meeting about how the investigations are going to relate to each other," she said.

"On the face of it seems like a duplication of effort, but whatever happens, lessons must be learned."