This was a speech in Parliment in 1979 about the introduction of Tachographs into HGV’s and Coaches…
"The tachograph has not had a good Press in this country. It has gained the wholly unmerited title of “spy in the cab”. This really is nonsense. The driver has the key to the instrument, and can inspect the record at any time.
Most of the information received is at present recorded manually on the driver’s daily log sheet. Like manual records, the tachograph is simply a means of enforcing drivers’ hours rules, in the interests of road safety.
In spite of this, some drivers are, I know, worried that this permanent record of the details of their daily work may result in prosecutions, months after the event, for some minor infringement of the law which went entirely undetected at the time and of which the driver himself may have been scarcely aware. Of course, the Government cannot in any way condone breaches of the law. But I believe that drivers’ fears are unnecessary.
The Department of Transport’s enforcement staff do not want to penalise the honest and careful driver who occasionally overruns his permitted hours by the odd few minutes. They want to catch the real lawbreakers, the irresponsible, and the drivers who work excessive hours.
I also expect that tachograph records will be little used in speeding prosecutions, and then only in conjunction with other, independent evidence.
The tachograph records give no information about where the vehicle was at the time when it was travelling at a given speed, and some evidence of this would be needed to establish whether any offence had been committed. A speed which is illegal for a heavy goods vehicle on an ordinary road may be lawful on a motorway.
Drivers’ fears of retrospective speeding prosecutions long after the event, based solely on tachograph records, are without foundation.
hansard.millbanksystems.com/lord … -recording
Well worth a look at the whole debate…