Two outstanding portraits by Irish artist Sir William Orpen will headline Sotheby's sale of British and Irish Art in London on Thursday, 10 May 2012.

Sir William Orpen, R.A., R.H.A. (1878-1931) is celebrated for his masterful portraiture. For example, a portrait of his wife titled In Dublin Bay sold for $1.37m at Christie's in 2010.

The May 2012 sale will bring to the market for the first time two fine portraits of The 4th Marquis and Marchioness of Headfort from a Private Collection. Portrait of Rosie, Fourth Marchioness of Headfort is estimated at £300,000-500,000 and Portrait of Geoffrey, Fourth Marquis of Headfort is estimated at £60,000-80,000.

These auctions will take place in May and November and will bring together the finest drawings, watercolours and oil paintings from the Pre-Raphaelites to the British Impressionists.

Portrait of Geoffrey, Fourth Marquis of Headfort by William Orpen

In addition, these two sales will have dedicated sections for Victorian Art, Early 20th Century British Art, Marine Art, Sporting Art, The Scottish Sale and The Irish Sale. Celebrating the distinct character of British and Irish Art will no doubt engage collectors worldwide, in response to the demands of new buyers who collect across a variety of genres.

The paintings are being presented for sale together for two reasons. The sitters, Geoffrey Thomas Taylour and Rose Boote, fell in love in the face of disrepute and disgrace, and it was a love that endured until Geoffrey's death in 1943.

Rose commissioned the portraits and they were almost invariably exhibited in the same exhibitions, although - save for one occasion at the Walker Art Gallery in Liverpool - not actually hung together. They were first exhibited at the Royal Academy in London in the 147th Summer Exhibition of 1915.

Rose Boote, later 4th Marchioness of Headfort (1878-1958) was a Gaiety Girl who sang the part of Maisie 'The Messenger Boy' in 1900 under her professional name of Miss Rosie Boote. She was the daughter of a comedian from Nottingham and a straw hat sewer.

William Orpen's Portrait of Rosie, Fourth Marchioness of Headfort

It is said that she so charmed the young Marquis of Headfort, Geoffrey Thomas Taylour (1878-1943) following their meeting in 1900 that he married her on 11th April 1901.

The marriage was supposed to have surprised and intrigued Edwardian society, and took place overcoming opposition from the family. Even Queen Victoria herself was even said to have commented on the match. The Marquis was from one of the most prominent Protestant families in Ireland and Rose was a Catholic.

As a Lieutenant in one of the country's most respected regiments, the 1st Life Guards, the Marquis had been destined for a distinguished career. Upon her marriage, Rose left the theatre and resided with her husband at Headfort House in Ireland and in London.