unknown mark next to EPNS mark

[tonyowen]

I've a number of pieces of cutlery from very early 20th century whose marks/stampings I cannot identify.

There is 101 or IOI next to EPNS [see attached image].

But I cannot find any reference or link to the 101 or IOI mark

Can you help?

Regards

Tony Owen, Ty Taurus, Bull Bay, Anglesey LL689SW