In British English it is no longer considered a solecism to use the plurals they, their, them, theirs as a generalized pronoun for words like eyeryone, everybody, anyone, anybody , etc.
( ( ( ( ( ( ( In ( British English ) ) ( it ( ( is ( no longer ) ) ( considered ( a ( solecism ( to ( use ( ( the plurals ) they ) ) ) ) ) ) ) ) ) , ) ( ( their , ) them ) ) , ) ( theirs ( as ( ( a ( generalized pronoun ) ) ( for ( words ( like ( eyeryone ( , ( everybody ( , ( anyone ( , ( ( anybody , ) etc. ) ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (PP (IN In) (NP (NNP British) (NNP English))) (NP (PRP it)) (VP (VBZ is) (ADVP (RB no) (RB longer)) (VP (VBN considered) (NP (DT a) (NN solecism) (S (VP (TO to) (VP (VB use) (S (NP (DT the) (NNS plurals)) (NP (PRP they)))))))))) (, ,) (S (NP (PRP$ their)) (, ,) (NP (PRP them))) (, ,) (S (NP (PRP theirs)) (PP (IN as) (NP (NP (DT a) (JJ generalized) (NN pronoun)) (PP (IN for) (NP (NP (NNS words)) (PP (IN like) (NP (NN eyeryone) (, ,) (NN everybody) (, ,) (NN anyone) (, ,) (NN anybody) (, ,) (FW etc.)))))))) (. .)))
It has become acceptable to substitute "they, their, them, theirs" as a generalized pronoun pronoun.
( It ( ( has ( become ( acceptable ( to ( ( ( ( substitute `` ) ( ( ( ( they , ) their ) , ) ( ( them , ) theirs ) ) ) '' ) ( as ( a ( generalized ( pronoun pronoun ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ has) (VP (VBN become) (ADJP (JJ acceptable) (S (VP (TO to) (VP (VB substitute) (`` ``) (S (S (NP (PRP they)) (, ,) (NP (PRP$ their))) (, ,) (S (NP (PRP them)) (, ,) (NP (PRP theirs)))) ('' '') (PP (IN as) (NP (DT a) (JJ generalized) (NN pronoun) (NN pronoun))))))))) (. .)))