Our country president Manmohan singh has just finished his 5 years tenure. Can I say Mr.Singh, you have been great in these 5 years or should I stick with 'was' rather then have been? Does it mean 'have been' is for recent past and common in British English? Guys I'm confused with this 'has been' use for past or present or might be used in both depending upon context.
John is right both in saying that you should seek professional advice if you plan to make a speech in Mr Singh’s presence, and in saying that the present perfect is probably what you need.
To answer the grammatical point specifically, one of the uses of the present perfect construction is to relate what has happened in the past to the present time. If you plan to speak or write about the president, his performance is clearly relevant at the time you are discussing it, and in that case the present perfect would be appropriate. You might therefore want to say, subject to the views of any professional adviser, something like ‘Mr Singh, you have given great service to our country over the past five years.’