Non standard shower hose replacement

[KCG]

Novice/new home owner - need to replace my shower hose, I've tried doing some research but not getting anywhere.

I have a bath tap mixer, I purchased 2 x 1/2 inch bsp hoses - https://amzn.eu/d/e17TFcZ and this https://amzn.eu/d/ekPuQ3m which both didn't fit (new hose too small for the bath connection)
The part I'm confused by is what do I actually need to measure to know what I need, is it the part with the hex nut or the part underneath?
I've attached pictures of the measurements of the hex nut and one without

I'm surprised it's non standard as the bathroom was fitted only a few years ago by previous owner, unfortunately I can't read the brand as it's corroded

 

[yorksbuilder]

Looks like you need 3/4" connection to the tap?
They are common with gravity fed systems where a larger bore allows a higher flow rate

 

[KCG]

Thank you for your response yorksbuilder, I was hoping that wouldn't be the case as I haven't found any sold online for 3/4. I'll have to find a connector I think.

Very bizarre to fit something that you can't replace

 

[yorksbuilder]

They would be available from plumbers merchants and maybe Screwfix

One of these may mean you can use the hose you have already bought:

https://www.amazon.co.uk/Shower-Adaptor-Female-Chrome-Reducer/dp/B07H8LFNKX

 

[KCG]

Thanks for your help yorksbuilder