My wife's mother was a resident of the UK and passed earlier this year. The Exceutor/Solicitor in the UK has told us that the real property will be "appropriated" (I don't quite understand the implications?) which will give rise to a capital gain. Non residents are not subject to UK capital gains but are there any Canadian tax implications?

You don't pay an inheritance tax in Canada. The deceased's estate pays a tax on the deceased's capital gains.