Firstly, lets try to identify the plug. Is it round with the two pins at the end, and does it have a metal contact on the sides at 90 degrees from the pins??
If you have a multimeter, check the earth between the side connections and the metalwork. If this is low resistance then that IS the earth and it is Class 1. If this is the case, then this I would guess is a european plug which should be cut off for UK use.
The next problem is the colour code of the cable. European cable is not always standard UK colours of Brown, Blue, Green/Yellow. If this is the case, it needs REPLACING with a new lead.
You might get it right, but if the plug needs replacing in the future, someone else might get it wrong!!!