I have searched in the forum and think I understand this, but am looking for confirmation.

I have a non o in my old passport issued in October 2015, with an arrival stamp until January.

The girl in HMPO office gave me the visa transfer template for CW and told me I need to go there.

BUT I don't have an extension stamp as I am still within the initial visa period.

From reading on here I can't transfer this and need to carry both passports.

Is this correct? I just go to the border and they stamp me out in the new passport and stamp me back in based on the still current visa in the old passport?

Help appreciated.

Visas cannot be transferred you have to use both passport on entry to the use the visa until it expires. They will stamp you into the country in your new passport.

The first time you leave the country you will show both passports and they will transfer your entry stamp from the old one to the new one and stamp you out of the country in it.

Thank you Joe, exactly what I was hoping for.

As a follow up qn - if I want to get an extension of stay at the end of the visa is there anything that needs to be done differently or is the process just the same?

You can apply for an extension of stay during the last 30 days of of the 90 day entries from the visa. You do not have to wait for your visa to expire.

When you apply for an extension immigration would do annotation of your visa in your new passport before doing the extension.