James Tabary probably began work on the interior of the chapel in 1683. The carving process continued very slowly and it was noted by an associate of Ormond in October 1686 that work ‘has gone on till alate [sic] most scandalously slowly, but now the work goes very briskly’. Despite the delays and soaring costs it was predicted that by Christmas 1686 they would have ‘one of the finest chapels consecrated the king has in his dominions’ (Ormond MSS, vii, 463). In 1687 the minute books of the governors of the hospital record that ‘James Tabarict [sic] carver’ was due the sum of £250 for ‘carveing, frameing and setting up the altar-peece, rayle, pannell and table in the chapell’ (NAI, minute book of the governors, RHK 1/1/1/, f. 35). It was also noted that he was to be paid more if further embellishments were made, and he may have received part of £809 that was paid for carving and joinery work at the hospital in 1686. In addition to the carving at the east end of the chapel interior, it is highly likely that he was responsible for the recessed wooden overdoors above the gates. There is no documentary evidence that Louis and John worked at Kilmainham, but it is plausible that they should have worked alongside their brother, with James in a supervisory capacity.
Tabary's work at the east end of the chapel at the Royal Hospital constitutes by far the finest ensemble of baroque woodcarving in Ireland, and is equal to some of the best surviving works in England and France. Some earlier historians of the Royal Hospital have mistakenly attributed the carvings to Grinling Gibbons, who was famed for his work at St Paul's cathedral, London. Tabary's composition is based around the Gothic east window and comprises two opposing groups of crisply carved Corinthian columns and pilasters, surmounted by further columns and heavy scroll motifs. He avoids overcrowding the chancel area with too much carving, and achieves the right balance between plain areas of panelling and swirling naturalistic foliage. The altar rail is composed of a highly individual type of chunky strapwork and heavy balusters, and behind is situated an exuberant five-legged communion table. Some of the wooden panels were rearranged in the mid nineteenth century in order to lower the window, but the overall effect is still impressive. The exterior wooden overdoors at Kilmainham are carved with martial implementa; one outstanding example shows the face of a warrior wearing a helmet made from a lion's pelt. In terms of quality and subject-matter these carvings would not have been out of place in one of Louis XIV's residences. Between 1687 and 1745 there were very few opportunities for craftsmen in Ireland to obtain similar lavish commissions for church interiors, but Tabary's carvings served as an inspiration for generations of native carvers. His influence can be seen in the organ case at St Michan's church, Dublin (dating from the early 1720s), and in carvings made for country houses such as Beaulieu, Co. Louth. No other works by Tabary are recorded in Ireland and it is unknown whether he stayed in Dublin or returned to London after 1687.