A £125,000 private treaty sale was completed by heritage agency Cadw on March 31.
The Saunders & Co stained glass panels were the final two from a 20-light window display produced for Lord Bute's private chapel at Castell Coch near Cardiff. It appears that Burges's wooden structure was impractical, possibly due to its exposed location in the roof of the Well Tower, and was pulled down some time before 1891, not long after the castle itself was finished. It is known only from a black and white photograph.
The 20 panels depicting a variety of Welsh and British saints and key biblical figures were recorded as being stored on site in 1901, but it is thought they were divided between family members when the third Marquess of Bute died.
Ten remained at Cardiff Castle while eight had previously been auctioned as a single lot at Christie's King Street and were purchased by Castell Coch, who have since built a replica chapel. The whereabouts of the two missing 2ft 4in x 15in (72 x 37cm) panels of St Michael, St Uriel and St Chamuel and Archangel Gabriel and St Joseph had been a mystery until they surfaced last year at Woolley & Wallis in Salisbury.
The vendor, a collector and scholar on the potter William De Morgan, found them and his initial research led him to believe they were the missing windows.
A visit to Cardiff Castle enabled Woolley & Wallis specialist Michael Jeffery to verify the windows next to the lifesize cartoon drawings held in the collection.
Negotiations with Castell Coch have been ongoing since the windows failed to sell with an estimate of £150,000-200,000 in the Arts and Crafts auction on June 23 last year. The panels will be displayed at Castell Coch in early summer.
