24" - limit - damn! I'm sorry to hear.
FWIW it has been concern of mine and others for years they would pull a stunt like that here in the States...like no civilians could have shorter bbls as LEO and Military ...meaning NO 18.5" or 20" bbls.
Hence the reason the 21" and 23" bbl set ups are being made up some of us folks...
Bird Guns 
Seriously either length is one helluva of a versatile shotgun, for upland, turkey, deer or critters - no matter how many legs.
Less monies-
If I were were you, as I and others have tested. Find a 26" bbl and buy and aftermarket screw in choke like Briley, Carlson, Colonial- etc that gives you Modified or Imp cyl+ performance.
More monies-
If you find a old bbl that was damaged at muzzle, measure to 25" [ wherever the attachment for rib allow, give or take a bit. Have a qualified Gunsmith install the aftermarket screw in chokes with again MOD or IMP Cyl+.
That combo is awesome. That constriction has proven to group slugs, and buckshot pattern so much BETTER than the high dollar name brand folks selling " specialty packages".
There is a reason the English or Bird Guns made by Rem, Win, Ithaca are NEVER seen for sale.