This is an early Irish surname. It is a developed form of the pre 10th century Old Gaelic Mac Breatnaigh, from 'mac', the patronymic son of, and Breatnaigh meaning a Welshman. Today this surname is chiefly associated with north-east Ulster, and was first recorded there in the mid 17th century, (see below). The name is akin to the surnames Walsh and Brannagh which are also forms of Breathnach. McBratney is particularly well recorded in church registers of counties Down and Antrim from the mid 18th Century. These early examples include that on October 20th 1741, of Alexander M'Bratney and Mary Morison who were married at Killyleagh, County Down, and on August 1st 1819 Rachel, the daughter of Samuel McBratney, was christened at the Presbyterian church, Dromara, in the same county. James McBratney and Mary Browne were married in Belfast, County Antrim, on December 25th 1848. The first recorded spelling of the family name is shown to be that of John MacBritany, in the barony of Glencarne, County Antrim. This was dated 1659, in the famous records known as Petty's Census of Ireland, undertaken during the reign of Richard Cromwell, known as 'The Lord Protector', 1658 - 1660. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.