Bit of a challenge! Lady Britannia maybe? [решено]

I found this whilst metal detecting on the South coast in Devon. Sorry it's rough but I'm just curious in case it was something nice! Any help appreciated

What is on the other side? 

What is the diameter? 

Any lettering visible? 

 Actually, it could be from Switzerland. 

A lady standing facing, holding a vertical spear in lowered right hand. 

Such as, with HELVETIA lettering below > 

Whoo you know I think you may have it! 

For that find you get my last Rolo! Thank you for your help, I am very happy 

 Thanks - I thought of there when I saw it was stars 

not lettering around the outside. I have been making this 

although a few of their coins use that design, 

so the diameter I mentioned earlier is needed, 

or that picture of the other side - where the denomination and year is. 

Sorry I forgot to say the other side is completely blank, I will get the Vernier caliper on it tomorrow and report back!

 OK - though as you are in UK what current coins is it near 

enough equal in size to - such as 1p or 10p or 50p perhaps? 

Good morning,

This is the other side of the coin and it measures 23mm if my tape measure is even remotely accurate. So I'm guessing the 1 franc coin? 

 Yes, that size would fit. There is a large 1 almost visible. 

N#185  [Years 1968-2026] 

Then your eyes are a lot better than mine ha thank you. What makes it even better is this was found 2 metres from a 1943 three pence. 

 Could be 1980 or 1986 date ? 

It's a shame it's so worn down, some detail would have been nice. 

 I see you have now added an avatar! 

A shame the Swiss coin was not also 1943 as 

N#184 

 they were silver [1875-1967] - the condition 

of your coin does not happened with silver coins. 

 Though indeed the lady looks like Britannia, 

her name is Helvetia > 

https://en.wikipedia.org/wiki/Helvetia 

 Lastly, from that there is 

CONFOEDERATIO HELVETICA 

on some coins. Those C H initials are on car stickers