Who is the Premier Baronet?

There are two types of "Sirs" in the United Kingdom. Baronets are hereditary knights, although not peers. Then there are the life peers, whose titles may not be inherited. Thus, baronets are neither fish nor foul. They are not peers of the realm and thus cannot be addressed as "Your Lordship." They would be called "Sir William, or whatever. However, their titles do pass from generation to generation. (Just to be clear, a baron is a peer, and a baronet is not.)

The Premier Baronet is the current holder of the oldest extant baronetcy in the realm. At the moment that would be Sir Nicholas Hickman Posonby Bacon, 14th and 15th Baronet. He inherited the baronetcy in 1982 upon the death of his father.

If you are wondering about the double numbers applied to him, Sir Nicholas is both the 14th and 15th Baronet of Bacon since the 8th Bacon Baronet of Mildenhall in the County of Suffolk (created in the Baronetage of England on 29 July 1627), additionally succeeded as the 7th Bacon Baronet of Redgrave in 1755 when his third cousin, the 6th Bacon Baronet of Redgrave, died without heirs. Also in case you are wondering, Sir Nicholas has four sons, so it looks like the succession is in good shape.

The original baronet was Sir Nicholas Bacon, 1st Bt., who was born about 1540 and was appointed to the baronetcy in 1611.