St. Patrick's blue

[4] The first record of blue as representing authority in Ireland appears in the late 13th century French roll of arms, known as the Armorial Wijnbergen.

[9] Shane Leslie speculated that the green-blue of St Patrick's blue might be "but a reminiscence of the woad-stain used by all colour-loving Celts".

[10] Constance Markievicz believed blue was "the old colour of Ireland" and incorporated it in the regalia of the Irish Citizen Army (ICA).

[11] Scientific analysis of the ICA banner, the Starry Plough, found it had originally been a rich deep poplin field of blue before being replaced with green in advance of being flown over the Imperial Hotel during the 1916 Easter Rising.

[14] More recently, Peter Alter[15] and Christina Mahony[16] have supported the historicity of the colour, while Brian Ó Cuív questioned it.

This is still the arms of the modern Irish state, and also appears in the lower left quarter of the Royal Standard of the United Kingdom.

[18] The Irish College in Paris, completed in 1776,[19] was renovated in 2002; the paint uncovered on the chapel walls was described as "St Patrick's blue" by a visiting journalist.

[21] At a "National Ball" during Edward, Prince of Wales' 1868 visit to Ireland, his wife Alexandra wore a dress of "St Patrick blue".

The Freeman's Journal criticised some of the code as difficult to comply with, but said 'Irish poplin ties of "St Patrick's Blue"—which we think looks rather green in a certain light—may [...] be had without much strain.

W. T. Cosgrave described the colour as "in perfect, traditional, national accord with our history and in close association with the most revered and venerated memory of our patron Saint".

[33][34][35] The uniform introduced in 1970 for Aer Lingus air hostesses and ground crew[36] combined green and St Patrick's Blue, described in The Irish Times as "a sparkling new colour".

[50] The Trinity College Dublin fencing club specifies that the azure in its colours is "St. Patrick's Blue (Pantone 295 as the Presedential [sic] Pennant)".