Interesting rifle. Some Lancaster records still exist, I had a look through some of the ledgers a number of years ago.
The guy who bought the company or name does not seem to have an internet presence but if you can track him down the number on the base of the trigger guard would make the rifle easy to look up in the ledgers, giving the date it was sold and perhaps the price, along with the purchaser of course.

Regards

AlanD
Sydney