Worthing, England - Private Postal Cover

I was wondering/hoping someone here might know a bit more about this cover I purchased today.

It dates from the 1971 postal strike, but I think it's interesting - Worthing is a little seaside town on the south coast of England, and it looks like they issued their own 'stamps', and had some sort of private postal service at the time.

I can't imagine actual post was carried with these 'stamps' on. What's the story? This cover and a couple like it I saw via Google, don't have delivery addresses on. Were they 'just for fun' or did they have any practical use?

First time I have seen this strike mail item.
There exists a catalogue of British Strike mail, which however, I do not possess.

Hi Rod,

Clive Smith compiled a series of handbooks on the 1971 Postal Strike Posts.

I have only one of these, Volume 5, which covers posts beginning with the letters "D" to "EM". This one was published in 1986.

G'day Nigel,
Thank you, I'll keep a lookout.
"Londonbus" was our "go to" man on Strike mail, not sure if he is still around?

I have this cover in my database.
Not aware if this is a Clive Smith production.