A) J.W. Laird was originally a Birmingham gunmaker at 10 Steelhouse Lane in 1848. It seems he, or more likely his son, moved to London, setting up at 6 Bishopsgate Without in 1889. The company was short-lived and is not recorded after 1896.
As your gun is a 10-bore it isclassed as an antique and if you do not wish to shoot it, it does not have to be on your shotgun certificate. Write to the police saying that henceforth you will be keeping it as a curiosity or ornament as per Section 58(2) of the Firearms Act 1968 and ask them to amend their records accordingly. Strike out the entry on your certificate and the job is done.