I have been asking this question myself for the last couple of years since it has been showing the English gun market getting weaker. I watch the auctions and for the last couple of years it has been my opinion that English gun prices have been dropping.
I don't want to claim to be an expert but I own a few English guns and when I bought them I had hope to their value rising. I would say at this time their values have fallen at least 25%.
Now I did not buy them at the time with resale in mind, but I did hope one day if I did I could turn a profit.
I don't blame the economy as much as I blame the times and how it is changing.
The new generation does not care for the refinement of Best quality as much as just functionality.
Also the decrease in game and places to hunt is taking it's toll.