Statutory Instrument 2000 No. 1562
The Air Navigation Order 2000
Pre-flight action by commander of aircraft
43 The commander of an aircraft registered in the United Kingdom shall reasonably satisfy himself before the aircraft takes off:
....
(c) that the aircraft is in every way fit for the intended flight, and that where a certificate of maintenance review is required by article 10(1) of this Order to be in force, it is in force and will not cease to be in force during the intended flight;
Note the use of the word "reasonably".
Mike