Citywire runs these examples..

http://www.citywire.co.uk/News/NewsArticle...&NewsPage=1

this case involves 70 year old guy with 45 year old thai partner.. but wants to leave his money to his son..note the rules about where the thai wife is domiciled.

"A discretionary trust generates a chargeable lifetime transfer and the taxation of this depends on any chargeable transfers in the previous seven years. A failed potentially exempt transfer (PET), where the transferor dies within seven years of a gift, is a chargeable transfer. This means that the periodic charge under a discretionary trust could be inflated over the next 80 years because of a previous failed PET; so it makes sense for Gerald to establish the discretionary trust before gifting the further £50,000 to his son.

Of course, the situation is complicated by the fact that Gerald made a previous gift to his son and put his house in joint names, but the historical position is something that cannot be changed. In addition, no spouse exemption is available and even if they got married, Hoa is not UK domiciled and can only receive £55,000 (plus the nil rate band) free from IHT."

(yep,they could have chosen a better name for the thai partner...)

It's a Viet name pronounced 'Hwaa'