Oggers,
The problem is you believe that it is still legal for GA pilots to carry out unapproved let downs below safety altitude.
Here is the relevant "present" rule (copied direct from the CAA website which links to a .PDF):
SERA.5015 Instrument Flight Rules (IFR) - Rules Applicable to All IFR Flights
(a) Aircraft Equipment
Aircraft shall be equipped with suitable instruments and with navigation equipment appropriate to the route to be flown and in accordance with the applicable air operations legislation.
(b) Minimum Levels
Except when necessary for take-off or landing, or except when specifically authorised by the competent authority, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State whose territory is overflown, or, where no such minimum flight altitude has been established:
(1) over high terrain or in mountainous areas, at a level which is at least 600 m (2 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft;
(2) elsewhere than as specified in a), at a level which is at least 300 m (1 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft.