Nice rifle. These photos look like a high grade Daniel Fraser take down rifle. It would the great to see where it has Lancaster on the barrel etc. Sometimes these rifles traded and retailed within the trade, so anything is possible. It certainly looks like it came out of Fraser’s shop. It’s a high grade gun.
It looks like the stock was refinished and a Griffin and Howe side mount added. The market is stronger for these in the US than the UK. In original condition, in the US, I think it could a $8-10k rifle at retail prices. The refinished stock and side mount might put it closer to ~$6-8k. It’s always better to have the rifle in hand to asses value but I hope this helps. Rookhawk will probably be along shortly…