Surnames were not known in UK until its conquest by the Normans. People who were “son of" or “daughter" is known or had a nickname. The nickname may have something personal that have been based on, say it was lame, or a big nose, or crooked, or had red hair, the list is endless. As was the Norman barons to UK, introduced the use of surnames. The British people have really taken hold of the idea, but not necessarily with the last name you chose to stay. Finally, the names were used, and stuck it.
It was much easier, was in the old days, because the communities were much smaller and everyone knew his name more than enough staff, because everyone knew his family too, that “son" would be sufficient for identification large number of people who would vote for their trade, Roger Fletcher, William the smith, and so on to be known. Eventually end up with Roger Fletcher, William Smith, Richard Redhead, and so on.
By the year 1400, the majority of British families, even those of the lowlands of Scotland, hereditary surnames were adopted. People were still taking the name again, as immigrants came to the UK bring with them new names. Many Scots, Welsh and Irish names are derived from the Gaelic name staff should take this into account when you need the Scottish or Irish genealogy. The Welshman took longer to adopt family names, but this was achieved in 1536, when Wales and England were united.
Family history and the search for family members was more of a minefield to change people and families in the past made their names. Of course I had no idea that people would be interested in the future, who they were and what they were called. Not always have to be a legitimate reason, they often do so simply because they felt like. Despite its name research focuses on family search family history, you should keep in mind that the name has changed over time.