Just a note that nobody has already mentioned ,knott axles are square section ,alko are sort of 5 sided awkward shape ,think i had a snipe trailer with Avonride axles with sealed bearings pre dating 2008 (which utilise hub pressed brgs and the one shot nuts )....your pictures just miss everything helpful ,shape of grease cap would be telling to some ! as would hitch style ,maybe avonride locking loop handle ,maybe the previus owner knows if it has castle nuts and split pins which if yes you have bought the right bearings
good luck .
If you get any awful delivery prices from mersea i can always collect and forward at cost !
https://www.merseatrailers.com/store/Axles-c39691221