P.S: The email mentions a transition period but doesn't provide any dates.
Dear Sir,
Thank you for your email correspondence of XXXXXX. I am sorry for the delay in replying to your email.
Please see the information we have received from our colleagues:
Applicants can currently submit either a blue or red certificate from UK NARIC, providing the certificate relates to the specific qualification obtained by that individual applicant.
There is currently a transition period in recognition of the reality that there are many blue statements already in circulation that applicants might wish to use. During this transition the Home Office will accept both UK NARIC traditional blue statements and the new red Visas and Nationality statements.
I hope this information is helpful.
Yours faithfully,
UK Visas and Immigration