Postmark help

[Marmalade501]

Hi, I wonder if anyone can help me. My friend has been receiving poison pen letters, the police have been informed but we have noticed different types of postmarks and a number underneath the date and time of posting. Would this be a post office id? Any help to try and narrow down who may have been sending these very distressing letters would be appreciated. I can post or send photos.

[TrueBlueTerrier]

If its a franking stamp the number will indicate which machine it went through.

A cancelled stamp will have details that can help identify which sorting machine cancelled it.

In both cases I would suggest that the Police contact the Royal Mail Security desk, despite the non descript name they are actually an internal police force and will be able to assist the Police in their investigations.

Good luck.

[Lounge Lizard]

Hi, I wonder if anyone can help me. My friend has been receiving poison pen letters, the police have been informed but we have noticed different types of postmarks and a number underneath the date and time of posting. Would this be a post office id? Any help to try and narrow down who may have been sending these very distressing letters would be appreciated. I can post or send photos.

Worth trying the Royal Mail Security desk but I very much doubt if the eight digit number as the last of the five or six lines of the ink jet postmark ( below "Royal Mail" / Mail Centre location / Date / Time ) could be of any significance.

[Snaggletooth]

If the item was posted in a post office and was sent recorded / special or larger than normal then the Post Office may have printed a stamp at the counter. This is printed on to a square self-adhesive label with a gold (or occasionally white) backing. The label has a large service indicator (e.g. 1LL for first class large letter), then under that a date of posting and the postcode area it was posted in (e.g. B1) then under that there is a session number corresponding to the till session number used at the Post Office. If you have a legible label in that format then the location and time of posting can be pinned down pretty easily by security. You should act fast though to give the PO a chance to recover CCTV images.

[Lounge Lizard]

If the item was posted in a post office and was sent recorded / special or larger than normal then the Post Office may have printed a stamp at the counter. This is printed on to a square self-adhesive label with a gold (or occasionally white) backing. The label has a large service indicator (e.g. 1LL for first class large letter), then under that a date of posting and the postcode area it was posted in (e.g. B1) then under that there is a session number corresponding to the till session number used at the Post Office. If you have a legible label in that format then the location and time of posting can be pinned down pretty easily by security. You should act fast though to give the PO a chance to recover CCTV images.

But these are "letters" so probably not "larger than normal" and being "poison pen letters" the sender will most probably avoid Signed For or Special Delivery for the best chance of maintaining anonymity.
Yes, the gold ( originally white ) Horizon labels ( e.g. 1LG for first class large letter ) could provide clues about the sender but, showing "the time of posting" ( or rather time of cancellation ) that's absent on Horizon labels, these are the unhelpful ink jet cancellations applied at Mail Centres.

[Snaggletooth]

I'll try and rephrase to make it clearer. In the unlikely event that the poison pen letters were sent using the Post Office Horizon labels then it's pretty easy to get time & date of sending and office of sending, and counter processed at, and from that to get CCTV images of the sender. If you know what you are doing and start the process promptly.

Could we have a picture of the marks please? Probably best to get on to the security desk ASAP too.