— Winston S. Churchill Prime Minister of the United Kingdom 1874 - 1965
In Churchill by Himself (2008), Appendix I: Red Herrings, ed. Langworth, PublicAffairs, p. 577 ISBN 1586486381; “Commonly ascribed to WSC, even by The Queen (Christmas Message, 1999). What Churchill actually said was ‘The longer you can look back, the farther you can look forward’”.
The attribution of the mistaken form of the quote to Churchill dates from at least 1959 https://books.google.com/books?id=QN3hAAAAMAAJ&dq=The+farther+backward+you+look%2C+the+further+forward+you+can+see&focus=searchwithinvolume&q=%22backward+you+can+look%22.