1916: 6 & 7 George 5, c.14: An Act to provide for the Time in Great Britain and Ireland being in advance of Greenwich and Dublin mean time respectively in the summer months.
[17th May 1916.]
BE it enacted by the King’s most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows:
[Time in summer months.]
1. — (1) During the prescribed period in each year in which this Act is in force, the time for general purposes in Great Britain shall be one hour in advance of Greenwich mean time.
(2) This Act shall be in force in the year nineteen hundred and sixteen, and in that year the prescribed period shall be from two o’clock in the morning Greenwich mean time on Sunday the twenty-first day of May until two o’clock in the morning Greenwich mean time on Sunday the first day of October, and His Majesty may in any subsequent year, by Order in Council made during the continuance of the present war, declare this Act to be in force during that year, and in such case the prescribed period in that year shall be such period as may be fixed by the Order in Council.
(3) Wherever any expression of time occurs in any Act of Parliament, Order in Council, order, regulation, rule, or byelaw, or in any deed, time table, notice, advertisement, or other document, the time mentioned or referred to shall be held, during the prescribed period, to be the time as fixed by this Act:
Provided that where in consequence of this Act it is expedient that any time fixed by any byelaw, regulation, or other instrument should be adjusted and such adjustment cannot be effected except after the lapse of a certain interval or on compliance with certain conditions, the appropriate Government Department may, on the application of the body or person by whom the byelaw, regulation, or other instrument was made or is administered, make such adjustment in the time so fixed as in the circumstances may seem to the Department proper, and if any question arises as to what Government Department is the appropriate Government Department, the question shall be finally determined by the Treasury.
(4) This Act shall apply to Ireland in like manner as it applies to Great Britain, with the substitution however of references to Dublin mean time for references to Greenwich mean time.
(5) Nothing in this Act shall affect the use of Greenwich mean time for purposes of astronomy, meteorology, or navigation, or affect the construction of any document mentioning or referring to time in connexion with such purposes as aforesaid.
2. This Act may be cited as the Summer Time Act, 1916.
Further reading: Wikipedia.