The history of electrical systems in Ireland tends to go like this:
1800s-1927 : Lots of small urban supplies, run by independent companies or, quite often, by City Councils. Many of these systems were DC and from what I gather, plugs, sockets and fittings were generally British style i.e. BS546 and its predecessors. Very little evidence of these systems remains, so it's hard to know exactly what was used. Although, I strongly suspect that there were very few sockets in use, with many appliances being connected via a bayonet light socket. Although, you do find evidence of the odd very old remnants of a 2-pin British style socket hidden away somewhere.
In 1925, the first major Hydro-Electric station was built on the Shannon by Siemens and in 1927 ESB, the electricity supply board, was established with the objective of electrifying the entire country.
ESB was established as a corporation, but it was state-owned and had some rather serious powers to override local planning/development laws to run cables across private land etc. Its predecessors, and the telephone companies, and the Post Office Telegraphs/Telephones office could only run cables along public roads.
ESB began rolling out the national grid, which was initially operated at 110kV 50Hz and the major urban centres were hooked up to this and converted to 220V/380V 50Hz supplies.
This saw the introduction of German-style side-earthed plugs i.e. Schuko and Siemens diazed fuses.
However, Schuko type plugs were not used exclusively, and BS546 was also considered to be acceptable and continued to be used along side the continental style sockets (although usually not mixed in the same installation).
The only major difference was that the wiring rules were more like Germany than the UK, so BS546 and Schuko installations were wired pretty much the same way i.e. 15A BS546 sockets sat on 16A radial circuits and the smaller plug/sockets were generally not used.
The only exception to this seems to have been where the smaller plugs were used to connect radios in kitchens to a lighting circuit.
I've never seen much evidence of widespread us of the 5amp plugs that seem to have been quite common in the UK.
In the 1950s and 60s a mixture of both continued to be used, but BS546 was definitely gaining popularity possibly due to the ease of access to supplies of fittings, boxes etc.
BS1363 began to appear in a wide-spread way in the 1960s and for similar reasons to the UK, it was adopted as standard to wipe out the mess of standards which had been in use previously.
It also meant that we had a single system of socket in use across the Island of Ireland as Northern Ireland, being part of the UK was also adopting BS1363 at the same time.
So, that's basically the history of how we ended up with BS1363
