On Thu, 17 Dec 2020 16:05:40 +0000, gareth evans
wrote:

On 17/12/2020 14:41, Peter Johnson wrote:
I have been trawling digitised newspapers for travelling post office
stories

I had a friend (RIP) who bought stamps at one minute past midnight
on the day of issue from the all-night post office (Trafalgar
Square?) and then rushed to catch the travelling post offices
leaving London in order to get the very special "AM" cancellation
because the TPOs franked mail with the date of leaving London
otherwise you'd get a first day cover postmarked the day before!

Yes, it was Trafalgar Square. The objective was to get the up trains
to London. The down trains had all gone by about 10.30.
Once, when the M1 was new, someone hired an e-type Jaguar because it
allowed them to get further from London and get postmarks that hadn't
been available previously.
There was, apparently, great excitement when the Forth Road Bridge
stamps were issued in Edinburgh at midnight, because they could chase
Scottish TPOs and get pre-dated covers from them.