The debacle, which has seen three Lancashire police workers facing disciplinary action for misconduct, will mean police could "struggle" to rebuild motorists' faith.

A probe focused on allegations that a speed camera had been wrongly set up and that paperwork had been wrongly processed by staff at the central process unit in Blackburn.

The joint investigation between the police and Independent Police Complaints Commission resulted in 545 speeding convictions being quashed, £35,000 in fines refunded and a further 2,115 tickets cancelled.

Motoring experts said police would find it difficult to rebuild motorists' faith in road policing following the scandal.

Elizabeth Dainton, research manager at the RAC Foundation, warned against over-reliance on speed cameras for keeping roads safe.

Ms Dainton said: "We do support the use of speed cameras where correct and appropriate but there needs to be traffic police on the roads to pick up offences such as drink and drug driving.

"Police will have a struggle on their hands to restore public confidence. Lessons need to be learnt and appropriate training needs to be in place."

The Evening Post revealed this month that there are now 184 officers patrolling Lancashire roads – a fall of 13 on the year before and the lowest since 2002.

Fylde MP Michael Jack questioned whether setting up cameras should be done by civilian staff instead of police.

The speed camera operator accused of wrongly calibrating a mobile camera in Penwortham and Blackpool was not a police officer.

Mr Jack said: "The Chief Constable has got to do everything he can to put in place policies which reassure motorists that the use of cameras is justified and done by the book in future.

"If it is not dealt with right, it will undermine the generally good relations police have with the public."

Ribble Valley MP Nigel Evans will write to Chief Constable Steve Finnigan to voice concerns about how cameras are used.

The Conservative MP added: "The fact three (police staff) have been found against is very serious.

"People will start to lose faith in the police.

"It's bad enough now – people already think they are nothing more than a cash cow for the Government.

"They raise millions but they are supposed to reduce accidents at black spots, not to raise money for the Government."

Figures show the number of fixed and mobile speed camera sites in Lancashire has increased from 63 fives years ago to 345 last year.

The number of people killed or seriously injured on Lancashire roads has dropped from 886 in 2003 to 863 last year but the number of those with more minor injuries following road accidents has risen from 5,238 to 5,471.

Andrew Howard, head of policy at motoring organisation the AA, said national research showed speed cameras could help to cut casualties by up to 100 a year at some sites.

A Lancashire Police spokesman said: "We will not be making any comment until after the disciplinary hearing."

The IPCC probe covered tickets processed between September 2006 to August 2007.

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