10 January 1840 the Uniform Penny Post was established throughout Great Britain and Ireland
Penny Post from Wikipedia    https://en.wikipedia.org/wiki/Penny_Post

SONGS ABOUT LETTERS AND THE POSTAL SERVICE
THE NEW PENNY POSTAGE Written and composed by Thomas Dibdin - 1839     https://monologues.co.uk/musichall/Songs-N/New-Penny-Post.htm
   
POST OFFICE SONG    by Slugs and Bugs    https://www.youtube.com/watch?v=W-XTwaphtx4
RETURN TO SENDER    by Elvis Presley    https://www.youtube.com/watch?v=-Ml1_SLU6x4
PLEASE MR POSTMAN     https://www.youtube.com/results?search_query=%22Please+Mr.+Postman%22
SIGNED, SEALED AND DELIVERED -   Stevie Wonder     https://www.youtube.com/watch?v=6To0fvX_wFA
LOVE LETTERS IN THE SAND -  Pat Boone     https://www.youtube.com/watch?v=gRDLTF0djHg
BECAUSE I LOVE YOU aka The Postman Song  -   by Stevie B  -   https://www.youtube.com/watch?v=Xc1uQI2XmZs
LETTER TO ME -   Brad Paisley     https://www.youtube.com/watch?v=RQ3bn7V0zdU
LETTERS FROM WAR  -   Mark Schultz     https://www.youtube.com/watch?v=RlP6igyDmAs
POSTCARD FROM PARIS -   The Band Perry    https://www.youtube.com/watch?v=cO3PQ5onovo <
POSTCARDS -   by James Blunt     https://www.youtube.com/watch?v=DB7jsjt4Uec
LETTER FROM AMERICA  -  The Proclaimers     https://www.youtube.com/watch?v=yy9GmieAEaQ
LETTER TO YOU  -   Bruce Springsteen and E Street Band     https://www.youtube.com/watch?v=AQyLEz0qy-g
STAN  -  Eminem     https://www.youtube.com/watch?v=kt14c7sYTFA
ANOTHER POSTCARD  -  Barenaked Ladies    https://www.youtube.com/watch?v=iVl6sU-7NPE
OPEN LETTER TO A LANDLORD  -  Living Colour     https://www.youtube.com/watch?v=odZErJf3hx4
LOVE LETTERS   -  Nat King Cole     https://www.youtube.com/watch?v=Sy4jDt6bkG8
CITY OF NEW ORLEANS  -      https://www.youtube.com/watch?v=TvMS_ykiLiQ
I’M GONNA SIT RIGHT DOWN AND WRITE MYSELF A LETTER -   Bill Haley and His Comets     https://www.youtube.com/watch?v=ZtHlSYVKdAU
P.S. I LOVE YOU -   The Beatles    https://www.youtube.com/watch?v=dd-3GSIvA00
A SOLDIER’S LAST LETTER -   Merle Haggard     https://www.youtube.com/watch?v=mD8bUX7wZi8
LETTER IN THE MAIL -   James Taylor     https://www.youtube.com/watch?v=R0gvsDBqdJw