This doesn't seem to work correctly for say London and Theran as the difference is not a round number of hours. Otherwise looks useful. Support for comparing with more than two parties would be nice
https://en.wikipedia.org/wiki/UTC%2B01:24
>On 5 August 1915, Warsaw switched to Central European Time, and the rest of Poland quickly followed suit.
Edit: Apparently Dublin Mean Time was even weirder than Warsaw's time zone, weighing in at UTC-00:25:21.
https://en.wikipedia.org/wiki/UTC%E2%88%9200:25:21
>UTC−00:25:21 was used in Ireland as Dublin Mean Time.
>Dublin Mean Time was introduced by the Statutes (Definition of Time) Act, 1880,[1] which also defined Greenwich Mean Time (GMT) as legal time in Great Britain. This Act replaced local mean time, which had been held to be the legal time since Curtis v. March in 1858, throughout the United Kingdom of Great Britain and Ireland.
>From 3:00 am Dublin Summer Time on Sunday 1 October 1916, the Time (Ireland) Act, 1916[2] changed the time used in Ireland to be the same as that used in the UK, both during daylight saving time and at other times.
https://en.wikipedia.org/wiki/Time_in_the_Republic_of_Irelan...
>John Dillon opposed the first reading of the Time (Ireland) Bill for having been introduced without consultation of the Irish Parliamentary Party; he said the different time in Ireland "reminds us that we are coming into a strange country".