http://www.legislation.gov.uk/asp/2007/1/section/44/notesCompulsory purchaseLegislationRoad buildingEnvironmental impact assessmentAirportsExplanatory Notes to Glasgow Airport Rail Link Act 2007Scottish ExecutiveKing's Printer for Scotland2018-08-31 1 15 January 2007 202 Section 44 requires the authorised undertaker to implement the rules (known as the “Crichel Down Rules”). The rules provide that in certain circumstances former owners will, as a general rule, be given the first opportunity to repurchase, at the current market value, land previously in their ownership which was acquired by or under threat of compulsion and which is no longer required for the purpose of providing the authorised works. The Circular applies to public authorities and makes clear that the rules (so called) are to be regarded as guidance rather than imposing an absolute requirement. By providing that this obligation to offer back surplus land will automatically apply, the Act overcomes any uncertainty concerning the identity (and hence public status) of the authorised undertaker and commits the authorised undertaker to implementing rules that would not otherwise be mandatory. 47 Set out in Scottish Development Department Circular 38 of 1992 in relation to the disposal of surplus land.