Your description is rather confusing. I will try to make as much sense of it as I can. You may want to get proper advice from a professional immigration advisor if you genuinely believe yourself eligible for British citizenship.
I was born within the Crown colony of Hong Kong on Mar 1973 and shall be a citizen of the United Kingdom and Colonies, consequent on my father achieving such a status by descent, at the time of my birth.
I had been born before commencement(BNA 1981) and become a CUKC by virtue of section 5 of the 1948 Act (citizenship by descent) as a result of the registration of my birth at the United Kingdom and colonies that section had been able to pass on citizenship to the me from my mother in the same way as my father at the time of my birth. If my father is a British Citizen (citizenship of the United Kingdom and Colonies) otherwise than by descent.
I am confused. You said that you were born in Hong Kong when it was a British colony and you would, therefore, have acquired CUKC status by virtue of s. 5 BNA 1948. Therefore, the ability (or lack thereof) of mothers to pass on CUKC status does not enter into it. Even if it did, you said that your mother and father both had CUKC status and had acquired it by the same means and were married, so you would have got from your father any status that your mother would have been able to pass on but for the gender inequality in the nationality law of the time.
Would I immediately before 1st January 1983 have had the right of abode in the United Kingdom by virtue of section 2(1)(a) of the Immigration Act 1971 as then in force (connection with United Kingdom through parent or grandparent) had I become a CUKC?
How would section 2(1)(a) of the Immigration Act 1971 as then in force have given you a right of abdoe in the UK? From what you have said, you were not born, adopted, naturalised, or registered in the UK. Rather, you had CUKC status by virtue of a connection with Hong Kong and not the UK itself. Your father became a CUKC by virtue of his birth in Hong Kong, not the UK itself.
If you were a CUKC but did not have a right of abode when the BNA 1981 came into force in 1983, then you became a British Dependent Territories Citizen by virtue of your connection with Hong Kong. This was not the same as British Citizenship. (Additionally, it would have been lost when Hong Kong was handed over to China. Those who were British Dependent Territories Citizens were able to register as British Nationals (Overseas) before the handover. For you to use BN(O) status to register as a British citizen now, you would have to meet the requirements of s. 4 BNA 1981, which would involve five years' residence in the UK as of the date of your application.)