Ok, I've got a couple of queries:

Q1) I've been at my company for 4 years and have just been given a promotion but verbally told I am on a 3 month probation. I've not had anything in writing to say I'm on a probation period, just a letter to sign (which I have and returned) to say I accept my new promotion. Does this mean It's not really a legitimate probation period?

Q2) If I don't have anything in writing to confirm my probation period, just a letter of acceptance stating the start date of my new role, and the 3 months comes and goes and no one mentions my probation period can my company still extend the probation period a week or even a month after my probation has been and gone?

Q3) I've since been told there is someone else (Employers friend ) after my role and I'm concerned that my employer may extend my probation period in an attempt to wait for me to make a mistake and use it as an excuse to not give me the promotion after all. Can my new promotion probation period extended without a legitimate criticism against my work? and if so, should I receive the explanation for this in writing?