Gents:
The double Jeffery in question that sold for 126,500 was one of two known rifles regulated for the 120-grain charge. It now i sin Europe and the other in New Zealand. I believe there is photo on the double rifles page of my website of the 120-grain Jeffery in NZ.

One can't judge market trends in double rifle value by looking at one of a kind rifles. They are sold and bought on whatever the buyer wants to give. I bid on the Larsen .600 above but was way off in my expectations in the value.

For nice doubles of a more common nature I would guess the prices are holding or a bit down. I base this on the fact that there are so many 5000-10,000$ new doubles out there the demand is down for the limited and finite supply of vintage doubles from the UK. So many folks want a double and want something new that is where the money is going. I have sold some common doubles (.500 bpe and .470 nitro) for less than they would have sold for five years ago. On the other hand, when I sell more desirable doubles (such as my .500 Watson, .450 no2 Lang, .475 no2 Scott) the market will hold the value. On the upper end of the spectrum my .600 or 4-bore, due to rarity and desirability, will increase in value and have done so the past few years. the new doubles, like a new car will depreciate a bit as so many are out there.

Just my two cents.
Cheers, mates.
Cal