Better a disputed Brontë than none?

It is well known what our opinion and the Brontë Society's opinion is about this alleged portrait of Emily Brontë (attributed to John Hunter Thompson of Bradford around 1840) recently auctioned at J.P. Humbert Auctioneers. This is the press release of its auction sale:

Emily Brontë 'Bonnet' Portrait sells in excess of £23000
A portrait of Emily Brontë has sold at a Northamptonshire auction house for £23,836 (premium inclusive) against a pre-sale estimate of £10,000-15,000. It will stay in England after a fierce bidding battle with a prospective buyer in America.
After much speculation over the past month as to whether the 7 'A' x 5 '/4" oil on board was of the reclusive English writer or not, the evidence as produced by the auctioneers seemed to stack up meeting much international interest and buyers in the room and online.
Auctioneer Jonathan Humbert of J.P. Humbert Auctioneers Ltd of Towcester said: "we are delighted with the result which seems to prove our contention that this was in fact a hitherto unknown portrait of Emily Brontë."
"During viewing, at least four independent authorities on the Brontë family concurred with our view, one of whom has written a definitive publication on Wuthering Heights." 

We wonder who these anonymous independent authorities are.