20a, Colston Road, London, SW14 7PQ

20a is a one-bedroom mid-terrace house in London (SW14 7PQ). It has a recorded floor area of 40 m² (around 431 sq ft) and construction records dating it to 1900-1929. At 40 m² this is the 4th smallest of 6 units on EPC record in the building, where floor areas span 36–54 m². The building's EPC ratings span D to C, with this unit at the top. The latest certificate (June 2020) shows a C (score 74). Earlier certificates rated it B (November 2008); the latest reading is one band lower. Between certificates, lighting went from Very Poor to Average; while wall efficiency dropped from Good to Very Poor and window efficiency dropped from Good to Average.

It hasn't traded since May 2009, a hold of 17 years that's notably long for the area. That sale fell during the post-crash dip, which often skews comparisons against later neighbouring sales. At 40 m² it sits well below the postcode median (92 m² across 21 EPCs), making it one of the more compact homes locally. Today's modelled estimate of £337,000 is 49.8% above the 2009 sale price. On a £-per-square-foot basis, the last sale (£523/sq ft) was about 28.5% below the postcode norm.