Philip Treacy le Bon, Kate Moss, Christy Turlington and Stella Tennant modelling in return for keeping Treacy's hats, which were all black. In 1994, he opened up his boutique at 69 Elizabeth Street, in Belgravia, London, right beside Isabella Blow's resicence at number 67. Treacy has designed hats for Alexander McQueen (another discovery of Isabella Blow), including his 1999 "white collection" for Givenchy Haute Couture in Paris, for Karl Lagerfeld at Chanel, and for Valentino, Ralph Lauren, Donna Karan, Versace and Rifat Özbek. In January 2000, he became the first milliner for 80 years to be invited to exhibit at the Paris
Seán Treacy Féin leaders. Treacy and Dan Breen were relocated to Dublin, where they were directed to operate with Michael Collins' assassination unit, "The Squad". The Squad's mission was to discover and assassinate British secret agents, political policemen and their informants, and to carry out other special missions for General Headquarters (GHQ) as directed by Collins. With help from police inspectors brought up to Dublin from Tipperary, Ormonde Winter's CIS spotted Treacy and Breen after their arrival in Dublin and placed them under surveillance. On 11 October 1920, Treacy and Breen were holed up in a safe house – Fernside – in