Payment of Foreign Death Duties

Can an English PR distribute the residue of the estate prior to determining if any foreign duty is owed?

My initial thoughts are that the PR needs to determine whether the foreign assets form part of the residue or form part of a specific gift. If they form part of the residue, then the foreign duty falls on the residue. Therefore, one needs to pay the tax prior to distributing the residue. If they form part of a specific gift, then the foreign duty is payable out of the specific assets, so one can distribute the residue prior to determining whether any foreign duty is owed.

I was uncertain regarding my conclusion as I understand an English PR has no duty to collect foreign assets unless they are needed to pay debts. Therefore, the idea that the English PRs should be paying foreign death duties out of the residue as part of the costs of realising the foreign assets seemed odd.