Implementation of new antique firearm calibers

[Mauserbill]

Hello
When is the official date of implementation of obsolete caliber deletions/additions and official publication
I have read through the Home Office document but can find no enactment date. The present section 58 caliber listings show no changes at this time. I ask this question as there are two of the nomination rifle calibers advertised as requiring a section one that I am keen to obtain on a section 58 without messing and costs of variation to my certificate

[The Event]

The Statutory instrument was made on 1st March and comes into effect on 22nd March. That should be the date the new list takes effect.
There has been no info yet on processes for putting removed calibres on to FACs.