I’ve owned Purdey guns that lettered as having Boss single triggers. The three pull design. Both pre WW1 iirc.

In reading the Purdey records many guns were ordered and finished in just a few weeks. I ask how this could be and the answer I was told is that in the high sales eras lots of single and pairs were built to relatively standard specs as time permitted. Example 28” double trigger game guns. Stocks were headed up and guns in the white. Customer was measured, stocker finished stocks to measured dimensions. Guns were hand carried to Kell’s shop and the engraving of a pair took only a few days. This was done by several people. One guy did trigger guards, one forend irons etc. A Kell engraved gun might have had 4-6 engravers. The records bear this out. Less than a week in Kell’s shop.

Guns finished in 45-60 days at times. Many buyers were not as sophisticated as today. The ones that knew what they wanted got it I suspect.

I’ve also been told that Purdey no longer has the jigs or blueprints to build the large framed 12 ga pigeon guns. Orders for them dried up long ago apparently. As I thought about that I don’t even recall seeing a post WW11 large frame gun. Probably a few out there but I may have forgotten them. Post war “pigeon” guns I have owned or recall seeing come in at 7# 4 oz to 7# 8 oz. I sold my last light framed pigeon gun this week. My pre war big framed guns are all at or over 8# with 30 or 32” barrels.

So yes, if a buyer wanted a Purdey actioned Boss it could be done in that era. Incidentally, Boss recently refused to build a Beesley actioned SXS I’m told on very good authority.