While it is more unusual to conclude a construction contract after the works have been completed, this practice is not unheard of. A contract can take effect retrospectively (Trollope & Colls Ltd and Holland & Hannen and Cubitts Ltd (t/a Nuclear Civil Constructors (a firm)) v Atomic Power Constructions Ltd per Megaw J pp.339; Tameside Metropolitan Borough Council v Barlow Securities Group Services). For example, on some construction projects, the parties may for commercial reasons commence the works under a letter of intent, before a formal contract is finalised. The court have recognised that, if the parties later enter into a formal contract, that contract may in some cases replace the letter of intent and apply retrospectively to the works carried out (see Practice Note: Letters of intent—construction). As for whether a contract intended to have retrospective effect is a ‘construction contract’