Brynderwen is 'set on the steep slope of a hill to the north of town [Llanidloes] facing South East; reached along a short access road.' It's thought to have been built in around 1890 (not shown on 1887 map) 'by the same person as no 2 and 3 Long Bridge Street, said to be a mill owner.'
The house has '2-storey and attic reflected pair with unusually exuberant High Victorian tiled detail.'
Cadw describes the exterior as 'Symmetrical 4-bay front with advanced and splayed outer bays with very steep hiped cross roofs. Slate roof with fishscale tiling, cresting and stock brick chimney stacks ornamented with red brick panels 2 French style dormer windows to front with ironwork volute and gable ornament. The main front is entirely faced in glazed bricks of various colours, predominately purple. Copious bands of classical and other detail - at cornice, entablature, lintel, cill and plinth level etc; band of fleuron panels above on 1st floor windows and cross pattern panelling between 1st and ground floors on the bay windows. The quoins are of deeply embossed stellar paterns in cream coloured terracotta creating a toothed edging. Horned sash windows, those to 1st floor have pedimented lintels with cream coloured dressings to central windows; pilasters to the bay windows. Cast iron trellised porch with twinned entrances and Rococo spandrel detail; high balustrade. Round arched doorways with keystones and cream coloured dressings; 4-panel doors and frosted glass fanlights. Tile hung 2 + 2-window left hand side with fishscale banding, pedimented lintels and splayed bay window; cross range stepped back beyond. Ruabon brick right hand side with similar window arrangement but more lavishly detailed, very ornate bargeboards. 2-window rear gable end and low outbuilding to centre.'
'The interior of Bryn Derwen also retains considerable original detail and Woodbourne is said to be similarly unaltered. The inner porch has brightly coloured wall tilling and this is continued up to dado height in the hall and up the staircase; similar fireplaces. Turned newel and unusual handrail with undulating edges. Brass knockers to panelled doors.'
Brynderwen is Grade II listed as 'an exceptional unaltered example of applied terracotta and tilework of the period.'
Source: Cadw Listed Building Report, no. 8385
RCAHMW, 2023