Time difference UK vs Ireland

[SteveD]

I have received transcripts of letters written to her mother by a distant relative describing her tour to Europe from Australia in 1912.

She refers to a ferry crossing from Stranraer in Scotland to Larne in Ireland saying, "...our watches were 1/2 hour ahead of Irish time...".

At that time was there a time difference of 30 minutes between what is now mainland UK and the island of Ireland? If so, when did it change?

[kempie]

Ireland adopted Greenwich Mean Time in 1916, supplanting Dublin Mean Time.

http://en.wikipedia.org/wiki/Dublin_Mean_Time

The Time (Ireland) Act 1916 changed the time used in Ireland to be the same as that used in Great Britain, both during Summer Time and at other times. This change took effect from 2am Dublin Mean Time on Sunday 1st October 1916. This was the time at which the change back from summer time would have happened; Great Britain had already gone back 25 minutes earlier, so Ireland had just one time transition that morning, where the time that would have been 3am according to the Summer Time then in operation in Ireland became 02:25:21 GMT.