Can you appear in MRCPsych Paper B with 12 months' of an experience only?

Can someone appear in MRCPsych paper B if she has done just MO-ship ( non-trainee) in a private sector for 12 months in psychiatry, especially if her supervisor is a Consultant registered with the Royal College of Psychiatrists?

Yes, you can as far as I understand, but you need to submit the confirmation of the following as stated on the RCPsych website :

Eligibility criteria for Paper B

1. You are in an approved training program. They recommend you have 12 months’ experience in psychiatry before attempting Paper B. OR:
2. You are in a post recognized by your hospital or trust as having contracted time and funding for educational training. Your job plan must include dedicated time for academic and educational activities such as attending journal clubs, grand rounds, attending an MRCPsych course of equivalent, study leave, and weekly educational supervision.