4.—(1) A notice under Regulation 3 of these Regulations shall—
(a)state the nationality and registration marks of the aircraft;
(b)state the type of aircraft;
(c)state that, by reason of default in the payment of a sum due to the authority for airport charges, the authority, on a date which shall be specified in the notice, detained the aircraft under section 14 of the Act, and, unless payment of the sum so due is made within a period of 56 days from the date when the detention began, or within 21 days of the date of service of the notice, whichever shall be the later, will apply to the court for leave to sell the aircraft;
(d)invite the person to whom the notice is given to inform the authority in writing within 14 days of the service of the notice if he wishes to become a party to the proceedings on the application.
(2) A notice under Regulation 3 of these Regulations shall be served—
(a)by delivering it to the person to whom it is to be sent; or
(b)by leaving it at his usual or last known place of business or abode; or
(c)by sending it by post in a prepaid registered letter, or by the recorded delivery service, addressed to him at his usual or last known place of business or abode; or
(d)if the person to whom it is to be sent is an incorporated company or body, by delivering it to the secretary, clerk or other appropriate officer of the company or body at their registered or principal office, or sending it by post in a prepaid registered letter, or by the recorded delivery service, addressed to the secretary, clerk or other officer of the company or body at that office.
(3) Any notice which is sent by post in accordance with the preceding paragraph, to a place outside the United Kingdom shall be sent by air mail or by some other equally expeditious means.