A word of warning to Scottish folks:
after a conversation with Fettes yesterday, it seems that they have been told by the Home Office that they can no longer grant condition 'o' on an FAC.
This is the condition that authorises you to obtain a new rifle on the condition that you dispose of an existing one. It is the useful condition that allows you to hang onto (and continue to use) a rifle up to the point where you can sell it and immediately replace it.
The lady I spoke to agreed that this was going to be extremely inconvenient for a lot of people, and indicated that there was going to be a meeting about it shortly.
However, anyone who has a currently active application for this type variation iis likely to be waiting a very long time. Best get them to send you back your ticket and go the normal route (sell the gun and apply for straightforward 1-for-1).