@bhaisahab, thank you. When people address someone as 'Sir', they usually use the first name or the full name. But when addressing Baron Desai, I have heard the debate moderator sometimes call him as 'Lord Desai' and sometimes 'Lord Meghnad'. This is the first time I have heard someone's first name being associated with the title 'Lord'. I wonder if the moderator is right or not.
"Lord Desai" would be the correct form of address.