Convert UTC to local time (in GMT time zone) taking into account daylight savings.

UTCToLocalTime

IF OBJECT_ID('[dbo].[UTCToLocalTime]') IS NOT NULL
	DROP FUNCTION [dbo].[UTCToLocalTime];
GO

CREATE FUNCTION [dbo].[UTCToLocalTime] (@UTC AS DATETIME)
RETURNS DATETIME
AS
BEGIN
	DECLARE @Hour AS TINYINT

	SET @Hour = 1
	--Regardless of year day light savings 
	--is applied between April and September
	IF (
			MONTH(@UTC) > 3
			AND MONTH(@UTC) < 10
			)
	BEGIN
		SET @UTC = DATEADD(HOUR, + @Hour, @UTC)
	END
	--Regardless of year day light savings 
	--is not applied between November and February
	ELSE IF (
			MONTH(@UTC) > 10
			AND MONTH(@UTC) < 3
			)
	BEGIN
		SET @UTC = @UTC
	END
	--If date variable is during March or October
	--assess if daylight savings is applied dependent on year
	ELSE IF (
			@UTC BETWEEN '2009-03-29 01:00:00'
				AND '2009-10-25 02:00:00'
			)
		OR (
			@UTC BETWEEN '2010-03-28 01:00:00'
				AND '2010-10-31 02:00:00'
			)
		OR (
			@UTC BETWEEN '2011-03-27 01:00:00'
				AND '2011-10-30 02:00:00'
			)
		OR (
			@UTC BETWEEN '2012-03-25 01:00:00'
				AND '2012-10-28 02:00:00'
			)
		OR (
			@UTC BETWEEN '2013-03-31 01:00:00'
				AND '2013-10-27 02:00:00'
			)
		OR (
			@UTC BETWEEN '2014-03-30 01:00:00'
				AND '2014-10-26 02:00:00'
			)
		OR (
			@UTC BETWEEN '2015-03-29 01:00:00'
				AND '2015-10-25 02:00:00'
			)
		OR (
			@UTC BETWEEN '2016-03-27 01:00:00'
				AND '2016-10-30 02:00:00'
			)
		OR (
			@UTC BETWEEN '2017-03-26 01:00:00'
				AND '2017-10-29 02:00:00'
			)
		OR (
			@UTC BETWEEN '2018-03-25 01:00:00'
				AND '2018-10-28 02:00:00'
			)
		OR (
			@UTC BETWEEN '2019-03-31 01:00:00'
				AND '2019-10-27 02:00:00'
			)
	BEGIN
		SET @UTC = DATEADD(HOUR, + @Hour, @UTC)
	END
	ELSE
	BEGIN
		SET @UTC = @UTC
	END

	RETURN @UTC
END