An interesting, lengthy and, ultimately, futile discussion. Consider two things:
Rule 29 of the Rules of the Air Regulations 1996 -
Without prejudice to the provisions of rule 5, in order to comply with the Instrument Flight Rules an aircraft shall not fly at a height of less than 1000 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 is flying on a route notified for the purposes of this rule;
(c) the aircraft has been otherwise authorised by the competent authority; or
(d) the aircraft is flying at an altitude not exceeding 3000 feet above mean sea level and remains clear of cloud and in sight of the surface.
Clearly, in the case of a 'self made' procedure, one is relying upon Rule 29(a) but, since GPS is not yet approved as a Class 1 aid in the UK, any legal procedure must be based upon a radio navigation aid and Rule 40 states that:
(1) Subject to paragraph (2), the commander of an aircraft shall not make use of any radio navigation aid without complying with such restrictions and appropriate procedures as may be notified in relation to that aid unless authorised by an air traffic control unit.
(2) The commander of an aircraft shall not be required to comply with this rule if he is required to comply with rule 31.
Therefore, any approach procedure that is not notified in accordance with Rule 40 is, unless authorised by an air traffic control unit, by definition, illegal.
Whilst anyone who thinks it is OK to conduct a 'self-made' instrument approach procedure is no loss to the aviation industry, the consequent loss of a perfectly serviceable aircraft, not to mention the innocent victims of such crass incompetence, is to be deplored.