I have been able to get this to work by

- dropping all subscriptions

- dropping all publications

- setting replication database option to false (sp_replicationdboption)

- setting replication database option to true

- creating all publications

- creating all subscriptions

I am going to put this down to being a corrupt distribution database, unless someone has a better reason for it.

thanks to anyone who has spent time thinking about this

Regards,

Phil