People are only just realising why they get letters with ‘P’ handwritten on front

According to postal workers, there's a very straightforward reason.

Many of us are ignorant to the swings and roundabouts a letter has to go through before it arrives in your letterbox.

Now and again, the envelope will pick up a couple of marks and scribbles as it traverses the globe or country on its way to the receiver.

One such common scribble is that of a large P scrawled across the front of the letter.

Thankfully, someone has taken to Reddit to get to the bottom of the mysterious 'P', and, as is always the case with the popular online forum, an answer has been delivered.

A user by the name of @designer_by_day asked: "Can anybody tell me why all my letters the last few days have had a “P” symbol written on them?"

They received over 350 comments in response, with the top comment receiving 1.6k votes.

"It means Parcel. For either yourself or the next delivery," they said. "It’s a reminder for the postman / postwoman."

A postal worker added: "Stops us from forgetting about it!"

A more comprehensive response came from someone with the username @whostolemycatwasitu, who wrote: "It's the postie's way of reminding themselves that when they come to post your letter there's also a parcel for you. That's so they don't post your letter then find out halfway down the street they forgot to knock and give you your parcel.

"Or sometimes they'll write P10 or something on the previous letter - that lets them know they have a parcel for next door (number 10) but no letter."

Others took the question as an opportunity for some gentle joking. One user commented: "Postman Pat is tagging your letters."

Another posted: "They have very politely opened it for you on your behalf to check that the contents are in fact private."