Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.
“Only” and “One and only” claims are regarded as either objective or subjective, depending on the context of the claim.
If an advertiser claims to be the only company to offer a service, or to offer certain benefits to the consumer, it is likely that this will be considered an objective claim, which the advertiser must be able to substantiate. An ad for TalkTalk which stated "We're the only major provider to guarantee no mid-contract price rises across all our broadband plans" was considered misleading by the ASA. The ASA considered that there was no accepted definition of a “major provider” in the broadband market, and that despite their lower market share, TalkTalk’s competitor Plusnet provided services to a large number of customers and had a significant advertising presence, meaning that consumers would be likely to identify then as one of the leading names in the industry. Because Plusnet also offered fixed term broadband packages, the claim was considered misleading (TalkTalk Telecom Ltd, 27 February 2019). Comparative “only” claims such as this will be subject to the comparative rules, and the basis of the claim should be clear, supported by evidence, and verifiable. See Comparisons: General and Comparisons: Identifiable competitors,
Another ad which stated “Dexter’s Surf and Activity Centre, Scarborough’s only Surfing GB accredited surf school academy, located right on the beach North Bay, Scarborough” was not considered misleading because, whilst there was another surf school in the Borough of Scarborough, it was the only surf school which can ‘academy’ level membership in the British Surf School Accreditation Scheme” (School & Hire Centre Ltd t/a Dexters Surf Shop).
If “only” and “one and only” seem to be another way of stating “best”, the ASA and CAP may regard the claim as an expression of opinion unless the rest of the advertisement gives the criterion for what then becomes an objective superiority claim. See also Types of claims: “Best”.