21a, Bostall Lane, Greenwich, London, SE2 0NH

21a is a mid-terrace house in Greenwich, London, London (SE2 0NH). It has a recorded floor area of 38 m² (around 409 sq ft) and construction records dating it to 1900-1929. At 38 m² this is the smallest unit on EPC record across the building (38–121 m²). The building's EPC ratings span E to C, with this unit at the top. The latest certificate (September 2023) shows a C (score 72). When first surveyed in May 2022 the rating was E, the property has climbed 2 bands since. Between certificates, hot-water efficiency went from Very Poor to Good, lighting went from Poor to Very Good and main heating went from Average to Good; while window efficiency dropped from Good to Average.

Untraded for 22 years, with the last transfer in December 2003. Across 2001–2003, sale prices on this property compounded at 22.3% per year. Today's modelled estimate of £305,000 sits 183.7% above the 2003 sale of £107,500. On a £-per-square-foot basis, the last sale (£263/sq ft) was about 32.7% above the typical sold price in the postcode. At 38 m² it sits well below the postcode median (81 m² across 36 EPCs), making it one of the more compact homes locally. Its energy rating outperforms most of the postcode (better than 78% of similar EPCs).