I’m taking this information from the Transport Act of 1968, I’m still trying to see if it has been amended as far as drivers of goods vehicles driving to domestic rules are concerned but I don’t think it has.
For the domestic rules the working day starts when you start work at the end of the last daily or weekly rest period.
As far as I can see as long as you don’t do more than 11 on duty and you have at least 11 hours rest between working days there’s nothing that says you cannot start earlier than you started the previous daily working period.
I’ve just checked the domestic regulations and as far as I can see both the scenarios you described would be legal.
from the “Transport Act 1968” - “Permitted driving time and periods of duty”.
Permitted driving time and periods of duty.
(1)Subject to the provisions of this section, a driver shall not on any working day drive a vehicle or vehicles to which this Part of this Act applies for periods amounting in the aggregate to more than ten hours.
(2)Subject to the provisions of this section, if on any working day a driver has been on duty for a period of, or for periods amounting in the aggregate to, five and a half hours and–
(a)there has not been during that period, or during or between any of those periods, an interval of not less than half an hour in which he was able to obtain rest and refreshment; and
(b)the end of that period, or of the last of those periods, does not mark the end of that working day,
there shall at the end of that period, or of the last of those periods, be such an interval as aforesaid.
(3)Subject to the provisions of this section, the working day of a driver–
(a)except where paragraph (b) or (c) of this subsection applies, shall not exceed eleven hours;
(b)if during that day he is off duty for a period which is, or periods which taken together are, not less than the time by which his working day exceeds eleven hours, shall not exceed twelve and a half hours;
(c)if during that day–
(i)all the time when he is driving vehicles to which this Part of this Act applies is spent in driving one or more express carriages or contract carriages; and
(ii)he is able for a period of not less than four hours to obtain rest and refreshment,
shall not exceed fourteen hours.
(4)Subject to the provision of this section, there shall be, between any two successive working days of a driver, an interval for rest which–
(a)subject to paragraph (b) of this subsection, shall not be of less than eleven hours;
(b)if during both those days all or the greater part of the time when he is driving vehicles to which this Part of this Act applies is spent in driving one or more passenger vehicles, may, on one occasion in each working week, be of less than eleven hours but not of less than nine and a half hours;
and for the purposes of this Part of this Act a period of time shall not be treated, in the case of an employee-driver, as not being an interval for rest by reason only that he may be called upon to report for duty if required.
