What would that purdey be worth with new barrels?
It was worth a hammer price of £15,000 on the day because there were at least 2 bidders willing to go to £14.5 K but only one who went to £15K.
At 3 times top estimate the bidders were probably attracted by the provenance and the whiff of scandal attached to a delightful if not very practical gun to shoot doves or driven partridge, and a rare if not totally original gun for the specialist Purdey collector.
It does not seem the sleeved barrels harmed the price, but if you paid Purdey to fit a set of new barrels (£30K ?) intrinsically it would be worth more but put back into auction you would be unlikely to recover any part of the cost of those new barrels.