Contracts governed by the Public Contracts Regulations 2015 (PCR 2015), SI 2015/102, often envisage a service arrangement that will last over a period of time and, because of that, the contract may contain sophisticated mechanisms by which various categories of change can be effected during the contractual term. This may include extensive clauses in relation to the extension of the contract. Whether the expired contract can be extended depends on the extension clause in question. If, for example, the clause provided that the contract could be extended after its expiration, the contract could be extended in accordance with PCR 2015, SI 2015/102. The relevant provision of PCR 2015, SI 2015/102, reg 72 sets out a comprehensive set of principles that will determine when a contract or framework agreement may be modified without a new procurement and when a new procurement procedure will be required.