I live just south of Manchester so come across quite a few examples of Newton guns as well as others from that area. I sold a Newton fairly recently that was a gun converted from pin-fire to central fire and aslo recentlu sold a Thomas Conway of Manchester hammer gun. I would guess that yours, by the stile was made in the 1870's to early 80's, if you have details of the original proof marks I might be able to be more specific. At first glance it looks as if it might be built on a Thomas action of 1871. I see some nice Manchester made guns on my travels. The only firm still in business there from that era is T.Stensby
http://www.wdlr.org.uk/stensby/ I don't know if they may have more knowledge of Newton guns. I still have a nice little double .410 hammer gun by Stensby. Some nice stuff came from both Manchester and Liverpool in the way of guns. Yours is a very nice example. Lagopus.....
