@Paul Willis said:
I have no idea about the answer to your question. It’s about four decades after my period of modelling interest.
However, I am a member of the GER Society, and will ask the question on their e-list for you. Hopefully, I’ll be back with an answer soon.
I’m pleased to say that GERS members responded swiftly, and have stated;
“My understanding is that all were delivered in lined BR Black, but at least 46465 was repainted in unlined BR black after a works visit to Darlington.”
“46467 was definitely lined black, at least whilst it carried the early BR emblem.”
I hope this helps with your modelling.