To those of you who have always wondered what James Blunt was referring to when he sang about a 'semi by the sea'; a semi is the abbreviation for a semi detached house. These are two properties build side-by-side sharing the middle wall usually associated with suburban areas. Semi detached is halfway between terraced and detached housing. The first semi-detached properties were built by John Shaw father and son in the 19th century in Chalk Farm, North London and were popular among the middle classes. Today, 32% of property in the UK are semis making them the most common property type.