The convention that "once a speaker always a speaker" is followed in-

In UK, there is a convention that "once a speaker always a speaker". British speaker is elected at the beginning of parliament by and from among the members of House of Commons. If the speaker of outgoing Parliament is still a member of the house and is willing to be re-elected, he can do so. Usually, he is re-elected as many times as he wants. A changes pf party does not make any difference.