Assets which are merely held in someone else's name are held on a "bare trust". A bare trust only exists where the beneficiary has full beneficial ownership of the trust property and has an immedidate absolute right to the trust property and any income derived from it.
The most common types of what are known as bare trusts in England and Wales exist when an adult holds trust property for a child under the age of 18 and the child's right to the trust property is absolute. Whilst these are commonly called bare trusts for minors they are not technically bare trusts because the child's right to the trust property is not immediate but contingent upon them reaching the age of 18.
A bare trust is also sometimes called an "absolute trust" or a "simple trust."
Bare trusts are not considered to be trusts (or settled property to use the technical term) for IHT purposes, and HMRC treats the assets as being owned by the beneficiary.