Sentence:  Almost daily something is reported which feeds this Catholic hope in England : statistics of the increasing numbers of converts and Irish Catholic immigrants ; news of a Protestant minister in Leamington who has offered to allow a Catholic priest to preach from his pulpit ; a report that a Catholic nun had been requested to teach in a non-Catholic secondary school during the sickness of one of its <WSD>masters</WSD> ; the startling statement in a respectable periodical that `` Catholics , if the present system is still in operation , will constitute almost one-third of the House of Lords in the next generation '' ; a report that 200 Protestant clergymen and laity attended a votive Mass offered for Christian unity at a Catholic church in Slough during the Church Unity Octave . 
Meaning of the word marked with <WSD> tags:  presiding officer of a school