The letter is from the elders' area on jw.org and is leaked by awake elders still in. It is a letter that is sent every year.
As the videos make clear, the letter itself is old news, it's basically a housekeeping matter. Also, information related to child abuse cases is not included as there are specific instructions in keeping certain information related to these cases.
As case, after case after case has demonstrated however, elders do either mistakenly destroy information related to child abuse, destroy data because they think a case is not considered to be child abuse and other circumstances.
The letter from the UK Inquiry body is telling organisations not to destroy documents. The British Branch have not made elders aware of this. They have sent any instruction qualifying the general instruction. Either they don't know about it or are maintaining a position of plausible deniability. Should the matter come up in the Inquiry then they could claim that elders did not see the letter and their instructions did not cover data related to child abuse cases. In this circumstance an elder would be on his own.
Under UK charity law the trustees are responsible for the actions of the charity. Since each congregation is a charity and the elders are trustees then individual elders can be held accountable for wrong actions by the charity. To this end the British Bethel is acting highly irresponsibly by not informing elders of the letter and it's implications.
Unfortunately the implications of this shall be lost on the vast majority of elders which makes the whole exercise even more critical for the sake of any victims who may be affected by naivety of local elders and the duplicitous and callous attitude of the WT Legal Department.