William FitzGuido explained

William FitzGuido, a Londoner, and Prebendary of Clondalkin,^[1] was appointed by Archbishop Archbishop Henry de Loundres to be Dean^[2] of St Patrick's Cathedral, Dublin in 1219^[3] and served until 1238.^[4]

References

1. "Fasti Ecclesiae Hibernicae: The succession of the prelates Volume 2" Cotton, H. p190 Dublin, Hodges & Smith, 1848-1878
2. https://www.stpatrickscathedral.ie/the-deans-of-saint-patricks-cathedral/ St Patrick's Cathedral, Dublin
3. "Fasti Ecclesiae Hibernicae: The succession of the prelates Volume 2" Cotton, H. p92 Dublin, Hodges & Smith, 1848-1878
4. Handbook of British Chronology By Fryde, E. B;. Greenway, D.E;Porter, S; Roy, I: Cambridge, CUP, 1996, 9780521563505