Elderly Honda mower battery?

[eldar]

I've inherited an old, 1984, Honda mower, an HR194. I've fixed it up so it runs OK. Just need to find a battery for the electric start. The existing one is dead, and an odd size. 12v,2.5ah, 100x55x80.

Google has turned up nothing for either that or supposed alternative versions.

Anyone any clue where I might find something suitable, before I start bodging...

[eldar]

Mr Pointy said:

This one says it's for an HR194 & is just 10mm bigger. Might it fit?

https://www.allbatteries.co.uk/tractor-ride-on-law...

It will indeed oddly, that site returns an access forbidden 403 from my ipad, phone and mac, but is fine for m/s firefox.

Thank you, appreciate the assistance