King Charles’s estate has announced it is transferring more than £100m, including funds collected from dead people under the archaic system of bona vacantia, into ethical investment funds after an investigation by the Guardian.

The surprise announcement comes amid growing pressure on the king over the Duchy of Lancaster’s use of funds collected from people who die in the north-west of England with no will or next of kin.

On Thursday, the Guardian revealed some of the funds were secretly being used to renovate properties that are owned by the king and rented out for profit by his estate. The duchy conceded that some bona vacantia revenues are financing the restoration of what it calls “public and historic properties”.

However the king’s estate has also been battling separate questions over its management of another portion of bona vacantia funds that are given to its charities.