There are two existing trusts, Trust A and Trust B. The assets of Trust A are held by an underlying company, Company A. Trust B does not have any assets yet
Now the assets of Trust A, held by Company, shall be transferred to Trust B. It is not yet clear, whether this will happen by way of transferring the assets from Company A to Company B, or by the Trustee of Trust A transferring the shares in Company A to the Trustee of Trust B.
Who is the Settlor of Trust B? From a logical point of view, I assume it is the Settlor of Trust A, but I am not sure who it would be if it was under legal scrutiny.
There are different tests for IHT, CGT and IT but I have little doubt that all would treat the settlor of Trust A as the settlor of Trust B regardless of how the assets are transferred.
It might only be different if Trust B gave full consideration for the transfer (say in the form of a loan note) in which case any person who added funds to Trust B (say a nominal £10 or the shares of Company B) may be treated as the settlor of the whole. In this scenario, there is still a risk of settlor A being treated as the settlor of Trust B for some taxes, particularly the Transfer of Assets Abroad legislation, income tax anti-avoidance provisions applying to non-UK structures.