The errant part arrived today, received a phone call from Dave himself yesterday morning, saying that the shipment had arrived. He even gave me free post, (I'd moved since placing my order and could no longer reasonably make it to the shop) I offered to pay the difference bit he declined.
So, I would absolutely recommend or use DCA again in the future, but only for their UK in stock items.
Unfortunately said item was an AK wooden stock, meant for a JG, with the part arriving being an SRC stock - no real fault of DCAs, they just get what they're given by the euro wholesaler, so it will require a bit of filing/trimming to fit. But it will finish the build.
Matter resolved.