Why doesn't C# detect that 1970/1/1 was under BST?
I'm working with a 3rd party API that returns Time of Day values as DateTime values filling in Jan 1, 1970 as the date part. So for 5AM, it will return something like 1969-12-31T21:03:00.000-08:00 The problem is that, when if the user was on London time, C# fails to apply BST adjustment for 1970-01-01. For example, 1970-01-01 5AM in UTC should be 1970-01-01 6AM in London. See conversion But, C# doesn't seem to apply this conversion: var utcTime = new DateTime(1970, 1, 1, 5, 0, 0, DateTimeKind.Utc); var britishZone = TimeZoneInfo.FindSystemTimeZoneById("GMT Standard Time"); var ukTime =