21 Castle Street, Aylesbury, HP20 2RE

21 Castle Street is a three-bedroom mid-terrace house in Aylesbury (HP20 2RE). It has a recorded floor area of 133 m² (around 1432 sq ft), construction records dating it to 1930-1949 and council tax band D. The latest certificate (December 2019) shows a D (score 60), on the cusp of jumping into the C band. When first surveyed in October 2009 the rating was E, the property has climbed 1 band since. Between certificates, roof efficiency went from Very Poor to Average, window efficiency went from Very Poor to Average and lighting went from Very Poor to Very Good; while hot-water efficiency dropped from Very Good to Good and main heating dropped from Very Good to Good. The recommended improvements would lift it to B (score 83), a 2-band jump. Other recorded features include a balcony.

At 133 m² the property is well over the postcode median (70 m² across 10 EPCs), placing it in the larger end of the local stock. Its energy rating outperforms most of the postcode (better than 70% of similar EPCs). 4 planning records sit against the property, 1 approved, 0 refused. Past consents include an extension, meaningful when judging how the property has evolved. The record references listed-building consent, which constrain future alterations. Across 2005–2020, sale prices on this property compounded at 2.1% per year. Today's modelled estimate of £406,000 is 31% above the 2020 sale price. On a £-per-square-foot basis, the last sale (£217/sq ft) was about 21.1% below the postcode norm. Last sale on file: £309,950 in May 2020.