Unnecessary earth wire?

Hi

I have a minor question about wiring. I need to rewire a double-insulated downlighter (used upstairs - so the unit is exposed in the loft). I will use 1.5mm2 6242Y T+E cable. As the unit is double-insulated there is no terminal for an earth wire. The terminal box on the back of the unit has no room to lose the earth wire. Should I cut the earth wire off, or sleeve it and bring it back out of the terminal box (leaving the sleeved wire exposed)?

I guess this is a minor question, but I would like to make a good job of it, so advice would be appreciated.

Thanks

David