unattend.xml regional settings

I'm trying to set up an unattend file but I'm having a small issue with the regional settings.

I'm using the UK English version of Windows 10 Creators Update (so all regions default to en-GB). If I use the settings below, the system default locale remains at en-GB but everything else is set to en-IE as expected.

Is there something I'm doing wrong? I know that the UI language is set to en-GB but this is the language pack so I don't think that's it.

<settings pass="oobeSystem">
	<component name="Microsoft-Windows-International-Core" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
		<InputLocale></InputLocale>
		<SystemLocale>en-IE</SystemLocale>
		<UILanguage>en-GB</UILanguage>
		<UserLocale>en-IE</UserLocale>
	</component>
	<component name="Microsoft-Windows-Shell-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
		<TimeZone>GMT Standard Time</TimeZone>
		<DisableAutoDaylightTimeSet>false</DisableAutoDaylightTimeSet>
	</component>
</settings>
<settings pass="specialize">
		<component name="Microsoft-Windows-International-Core" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
		<InputLocale>en-IE</InputLocale>
		<SystemLocale>en-IE</SystemLocale>
		<UILanguage>en-GB</UILanguage>
		<UILanguageFallback>en-US</UILanguageFallback>
		<UserLocale>en-IE</UserLocale>
	</component>
</settings>

Just to add to this, I used the same file on Windows 7 and it works fine.