It is not unusual to see covers from Halifax with a cachet reading "transmission delayed....". As convoys sailed from Halifax roughly each week I was looking for some info as to how long the letters were delayed for. So far I have only seen one suggestion that it was until the convoy had arrived in the UK.
Has anyone any info or a like to any article on this subject
Sorry I should have been much more specific. I knew what I wanted to find out but did not make it clear
The two line cachet TRANSMISSION DELAYED / FOR PURPOSES OF SECURITY is not uncommon on mail from Halifax. However it is not found on all mail. The 2 examples I have are postmarked just prior to the sailing date for a HX convoy to the UK but are addressed to the USA. You presumably would not expect this cachet on mail to the UK.
I understand that the mail could be delayed until any info it may have contained about a convoy would be out of date but as convoys left every week or so I woundered how long the security delay may have been. I cannot find any info on the internet.