ShyTorque, methinks some humble pie is in order. From something called The ANO:
Minimum height
33 (1)
Subject to paragraphs (2) and (3), an aircraft shall not fly at a height of less than 1,000 feet above the highest obstacle within a distance of 5 nautical miles of the aircraft unless:
(a) it is necessary for the aircraft to do so in order to take off or land;
(b) the aircraft flies on a route notified for the purposes of this rule;
(c) the aircraft has been otherwise authorised by the competent authority in relation to the area over which the aircraft is flying; or
(d) the aircraft flies at an altitude not exceeding 3,000 feet above mean sea level and remains clear of cloud and with the surface in sight and in a flight visibility of at least 800 metres.
(2) The aircraft shall comply with rule 5.
Now, I would agree that there is a difference between the law and common sense. Personally, I wouldn't be doing the 800m bit at 140kts with various pointy things sticking-up out of the ground.