It would be of great help if you could analyze my case:

My grandfather (mothers father) born in London UK 1920
My mother born in Rio, Brazil 1951
*registered in the consulate in Rio along with her 2 male brothers (my uncles)
I was born in Rio 1977 (British Citizenship denied, my grandfather tried registering me in nov. 1982 based on the 1981 act and had no success)
My cousins born in Rio 1981, British Citizenship granted, they where successfully registered in the British consulate in Rio.

According the UKM form guide it is quite clear I am eligible if:
"you would have become a citizen of the United Kingdom and Colonies by
descent if women had been able to pass on citizenship to their children
in the same way as men at the time of your birth"

What are my chances if I apply?

Areas of Expertise: 

Public Answer: 

Dear Sir, from the information provided above, you may possibly be eligible to apply for a UK Ancestry visa.  Nonetheless, a member of our British nationality advisors shall contact you to discuss your eligibility for Adult Registration as a British Citizen and your eligibility for a UK Ancestry visa. 

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