A dictionary of Proverbs (Oxford Paperback Reference)

NEW brooms sweep clean
The phrase new broom (one newly appointed to a position who makes changes in personnel or procedures) derives from this proverb.

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  1546 J. HEYWOOD Dialogue of Proverbs Il.i. F3V Som therto said, the grene new brome swepith cleene. 1578 LYLY Euphues I. 232 Ah well I wotte [know] that a newe broome sweepeth cleene. 1616 J. WITHALS Dict. (rev. ed.) 569 New bromes sweepe cleane, yet old friendship still retaine. 1776 G. COLMAN New Brooms! 15 I am glad he is gone—Glad!—To be sure. New Brooms, you know. 1877 J. A. FROUDE Short Studies 3rd Ser. 55 New brooms sweep clean. Abbot Thomas, like most of his predecessors, began with attempts at reformation. 1979 F. OLBRICH Sweet & Deadly iv. He was all right at first. It was a case of a new broom sweeping clean. "improvement; innovation
  

What is NEW cannot be true

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  1639 J. CLARKE Paramiologia Anglo-Latina 228 The newest things, not always truest. 1791 J. BOSWELL Life of Johnson II. 283 I found that generally what was new was false. 1880 J. NICHOL Byron ix. We are told.. that he knew little of art or music. .. It is true but not new. But when Hunt proceeds to say that Byron had no sentiment.. it is new enough, but is manifestly not true. 1928 Times 4 Feb. 8 Sir Arthur Evans has fallen a victim.. to the old slogan’What is new cannot be true.’ "innovation
  

NEW lords, new laws
Cf. a 1450 St. Editha (1883) 96 Willyham Conquerour was made here kyng, And made newe lordus and eke new lawe.

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  a 1547 E. HALL Chronicle (1548) Hen. VI 169 Tholde spoken prouerbe, here toke place: New Lordes, new lawes. 1824 SCOTT St. Ronan’s Well II. i. But new lords new laws—naething but fine and imprisonment, and the game no a feather the plentier. 1874 T. HARDY Far from Madding Crowd I. viii. ‘I was lately married to a woman, and she’s my vocation now.’ . . ‘New lords new laws, as the saying is.’ 2004 News Bulletin (dateline: Sochi) 28 Mar. (Interfax) The EU presidency rotates every six months. ‘As a Russian proverb says: new lords, new laws. The EU has new priorities with every new president. It is difficult to work in these conditions.’ "change; circumstances