Something of great concern to companies is whether their drivers are working for another company on their weekly rest days. Some drivers do go to agencies and do not take the required weekly rest. This of course can cause problems for their employer.  

1a. Without reasonable excuse return any chart which relates to him to his employer within 21 days of completing it

1b. Where he has two or more employers where he is employed as a driver, notify each of them of the name and address of the others.

2. If the employer of drivers of a vehicle to which this section applies fails without reasonable excuse to secure that drivers hand in their charts he shall be guilty of an offence.

3. Where a driver of a vehicle to which section 97 applies has two or more employers by whom he is employed as a driver of such a vehicle, then the employer for the purposes of 1a and 2 above of this section will be construed as the employer who was first to employ him as a driver.

Therefore, if your driver is in regular employment with you and works for another company at the weekend for example, on a casual basis then his charts, whilst working for this second employer must be returned to you.  Also if it is the last chart from the previous week, then he must carry this chart with him not the last chart when he worked for you.

One way for companies to cover themselves is to get the driver to complete a blank chart for the days when he is supposed to be off duty and entered his name, date and 'rest day' and sign the chart - (most important to prove that he made out the chart, not someone on his behalf).  

If he subsequently works for another company and is stopped by the Ministry, then his employer can produce these charts to show that he had been on weekly rest from his normal employment.