What Rudyard Kipling Thinks of the Pocket Kodak.
The pattern
This still is filed under Celebrity endorsement.
Define
A named, recognizable person lends their reputation to the claim. The name is the proof.
Mechanism
Transferred authority. The reader believes the person first, the product second. Fame or office does the work a peer testimonial does not.
Verdict
The endorser is actually known to the buyer
Why it works
The entire ad is one borrowed judgement, and the layout enforces it - the testimonial is set larger than the headline and far larger than the brand, so the reader's attention lands on the endorser's words rather than the seller's. Reproducing the signature in facsimile script is the proof device: it converts a quotable line into a document. The quote is also carefully modest, praising the little camera's work rather than making a claim about the product line, which is why it reads as opinion rather than copy. The product is reduced to a thumbnail engraving and a one-line spec, because size and price are the only facts the endorsement leaves to settle.
Steal this when
You have one credible name on record praising your product and your own claims are not being believed. Give the quote the whole page, set it larger than anything you wrote yourself, reproduce the signature, and reduce your own product information to a line of specification and price.