Partridge v Crittenden  1 WLR 1204 is a landmark case that established the principle that an advertisement is generally an invitation to treat and not an offer, unless it is clear from the language used that it is intended as an offer.
In this case, the defendant, Mr. Crittenden, had placed an advertisement in the periodical "Cage and Aviary Birds", under the general heading "Classified Advertisements" which contained "Quality British A.B.C.R. ... Bramblefinch cocks, Bramblefinch hens 25 s. each". In no place was there any direct use of the words "offer for sale"
Partridge was charged by Crittenden, on behalf of the RSPCA, with illegally offering for sale a live wild bird which was not a close-ringed specimen, bred in captivity, contrary to s. 6(1) and Sch. 4 of the Protection of Birds Act 1954.
The court held that the advertisement in question constituted an invitation to treat and not an offer to sell; therefore the offence with which the appellant was charged was not established.
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