How do I appeal the conclusion on my CF83 application?

My CF83 was rejected by the caseworker on the basis of my employment whilst in the UK (I left the UK in 1986). The NI38 booklet states that immediately before going abroad I had to have been ordinarily an employed worker. At the time, I had two part-time roles which I worked in conjunction with each other, from which I had to resign. I was therefore 'an employed worker' immediately before leaving. As HMRC will hold records confirming that I paid NI contributions until leaving the UK, I dispute the caseworkers decision and believe that I am eligible to make voluntary Class 2 contributions. How do I appeal?

Hi, 

If you do not agree with our opinion that you were not employed before leaving the UK, please put your reasons in writing to our international caseworker team who will review any additional information you provide against the information we hold on our records. Please quote your National Insurance number in your letter and include any copies of evidence you have to support your request to reconsider your application. The address to write to is:  

International Caseworker
PT Operations North East England
HMRC 
BX9 1AN

Thank you.