Fit UK Plug on Allo Nirvana

[TuckerJenkins]

I've had an Allo Nirvana with a 2 pin euro ac plug and uk adapter for a few years now and very nice it is too.  I went to fit a UK plug and was surprised to find that the ac cable was 3 core with an earth wire.  When the earth switch on the Nirvana is in the on position the earth wire is connected to the Nirvana board even though there is no connection at the euro plug end, this has baffled me but in any case I don't know if it is best to connect the earth at the UK AC plug end or not ?

[One and a half]

If the earth wire is provided, it should be connected to the earth pin.

[TuckerJenkins]

Thanks, that may seem the obvious answer and hence a dumb question but I was confused as the earth is not connected at the original 2 pin euro plug.