The surname Bradburn appears to be a locative/toponymic one (ie based on the name of a particular place) and is derived from the Old English words 'brad' (=broad) and 'burna' (=stream); the place by the broad stream. I believe that it has its main origin in the village and parish of Bradbourne in Derbyshire, England, where a broad stream can still be seen today. It probably also began separately in Bradbourne, Kent, England, although it is more difficult to trace a Bradburn family from here.
Until now the accepted version of the origin of the family name has been the one given by Sir Humphrey Bradburne to the visiting Heralds in July 1569. Sir Humphrey said that the first person to hold the family name was a man called Gerard or Godard who lived in the thirteenth century and was the grandfather of the well-documented Roger. I have not yet found any trace  in contemporary documents of this Gerard or Godard, but by studying over 400 documents from the twelfth and thirteenth centuries I believe that I have been able to uncover the real origin of the family.
The person who began it was Sir Robert de Esseburne (c. 1200 - 1253) who lived in Esseburne (now called Ashbourne, Derbyshire, England) and was steward to the Earl of Derby, a Justice of the Court of Common Pleas and King's Constable of the High Peak.In 1238 Sir Robert was granted the Manor of Bradeburn (now Bradbourne, Derbyshire, England and only a few miles from Ashbourne) and in 1250 he purchased the land at Hulland nearby on which the family later built its second house, the Hough. I believe that Sir Robert is the Robert de Bradeburn mentioned in several undated documents of this period. Sir Robert died in 1253 without children and his heir was his brother's son, Henry de Esseburne. In 1258 Henry bought three parts of a knight's fee in Bradeburne and around 1260 is mentioned as Henry de Esseburne, Lord of Bradeburne. He is also probably the Henry de Bradeburne who witnessed a document in around 1265. Henry died before 1269. His son was Roger who is probably the person mentioned as Roger de Esseburne in the 1270's but from 1284 he becomes Roger de Bradeburne. Over the next 34 years there are more than 80 documents mentioning Roger (later Sir Roger) de Bradeburne until his death in around 1318. In the thirteenth century inherited surnames were only just beginning and this gradual transition from the use of the village where they originally lived (Esseburne) to the village in which they became Lords of the Manor (Bradeburne) would not have been unusual.
The Derbyshire land-owning family which descended from Sir Roger, known first as de Bradeburnes, then de Bradbournes then as Bradburnes and finally as Bradburns, can be traced through to around 1600, and I believe that most of the British Bradburns alive today are descendants of this Derbyshire family. The ornate tombs of two of the last landed members of the Derbyshire family can still be seen in the church of St Oswald in Ashbourne, Derbyshire.
The greatest concentrations of the surname in recent times are in Lancashire and Cheshire, England and in the area around Birmingham, England and I believe that the ancestors of these present-day Bradburns migrated out of Derbyshire from the middle ages onwards. I am trying to trace this migration.
There was another manor with the name of Bradbourne in Kent, England and documents from the thirteenth century list a number of people from this manor who were called de Bradeburne or de Bradbourne. The early (c.1600) parish registers for the nearby parish of East Malling contain several Bradbourne baptisms, so I believe that an inherited surname may have developed from there also. This may be the source of several Bradburn families in nearby London. . A 'de' plus a placename was often used in legal documents just to distinguish people from those of the same first name who lived in another village.