HAVING just driven past the almost-permanent 'mobile' speed camera by the side of Cherry Tree Cricket Club, in Preston New Road, Blackburn, I wonder if the frequent use of these mobile cameras suggests that the fixed ones are no longer generating the required revenue due to local people being aware of their location.

I have a 'Snooper' device (legal following an appeal court ruling in 1998) in my car which can inform me, from the strength of signal, whether a speed camera is switched on, passive -- switched on but has no film -- or fully operational.

I do not use this device not so that I can zoom around breaking the law, but to allow me to detect cameras as I frequently drive around new locations and, more importantly, to remind me to stick within the speed limits, which have been set for the safety of all road users, including pedestrians.

Certainly, over the past few months I have noticed that very few of the fixed-site speed cameras in the town are ever switched on, never mind fully operational. Why?

And before the safety campaigners and do-gooders get on my case, let me state that I fully support the use of speed cameras in areas near schools, etc.

My comments are not those of a motorist who has fallen foul of the law, as I have been driving 30,000 miles a year for more than 25 years and still have a clean driving licence.

No-one can condone excessive speeds, but the positioning of these mobile sites, on the brow of a hill or in subdued light under a bridge, would suggest they are to trap, not to deter.

ANDREW SMITH, Kentmere Drive, Cherry Tree, Blackburn.