Hi George,
No, AMAL carbs were not in common use until 1930, and yours is later than that.
In 1913 Douglas used either their own "salt and pepper" carburettor, or an AMAC that was specially made for them featuring an exhaust-heated muff (see the carb on the left below). The AMAC is probably easier to find and a better carb to use, but the Douglas item is better looking and a nice talking point.
If it matters, there were several versions of the Douglas AMAC, roughly in the veteran era: 1913-14 had the large hexagon fitting under the mixing chamber, whereas for 1915-1919 the mixing chamber was a smooth, slim casting under the slides like the carb on the right.
Nice bike, by the way. Unusual to have the cone clutch.
Cheers
Leon