Here is a very nice little 28 bore John Harper BLNE. I have made a study of the Harper gunmaking family, there were three generations of John Harper, though the youngest was known as Norman.

Their own name guns come along rarely. However, they made excellent Birmingham guns for demanding taskmasters in the London trade, who put their names to the guns. These included Beesley, Churchill, Wilkes, Robertson (Boss), Pape and Woodward.

At $1,962 in the UK, plus shipping, this gun would still come out a good deal cheaper than the others suggested: https://www.guntrader.uk/guns/shotguns/harper-j/side-by-side/28-gauge/220201122950109

[Linked Image from jpgbox.com]

Since the gun is located just down the road from Diggory Hadoke, you could ask him to look over it, broker the deal and send it over to you in one of his consignments.

Tim