In 1987, or thereabouts, Lord NaTCH bought an early '60s Wharfedale catalogue in a Worthing bookshop for 50p.  It really is a magnificent thing.  "Wharfedale" gold blocked on to a cover rolled to make it look like leather!

 
In amongst the oscillograms, conical diffusers and Overseas Agents (NEW ZEALAND . . . . Alan R. Seccombe Esq., 2 Mt. Royal Avenue, Mt. Albert, AUCKLAND S.W.2) is ...

... this pic of the Wharfedale lab.
When Wharfedale old boys John Dibb and Mr/Dr Peter "Mad Dog" Fryer saw it  they immediately said "It's Ken.  Good God he was going bald even then!"

And while we're on the subject why did older speakers have square magnets?  Surely it made the magnet more lossy?

B&W's Steve Roe's has opined maybe it was because it was easier to crop the square end plates rather than turn or stamp circular ones?  Works for me. 
UPDATE: Dr John "Bowtie" Dibb has emailed us to opine that square end plates were used to save material.  Sounds convincing.  Although cropping a square end plate would be cheaper than stamping wouldn't the necessary sharp edge fettling consume the saving?
It has been Lord NaTCH's experience that an awful lot of what gets done in loudspeaker factories gets done because it's done.  People do right or wrong things for the wrong or right reasons or do dubious things for even more dubious reasons supplied by an engineer who left fifteen years ago.  Perhaps square end plates fall into this category?