[suvelx]

Mostly banks. Insurance has a part to play.

My understanding is:

In 2018 the government banned ACM cladding.

Shortly afterwards RICS (Royal Institute of Chartered Surveyors) developed the "External Wall System" or "EWS-1" form. Which is a means of assessing the risk of cladding (external wall systems) to a building. This was not a legal requirement. It is merely a tool to assess risk. It does not even specify the credentials required to issue one, just "suitably experienced".

Surveyors carrying out an EWS-1 form would effectively be on the hook for any damages if they made the wrong call, This ended up being reflected in their insurance, so most if not all would perform a full top-to-toe inside-out fire-safety survey. These full surveys have resulted in other defects in most buildings being found. Combustible material used in balconies, insufficient fire and smoke barriers between dwellings, faulty or incorrectly installed fire doors. Note These 'defects' aren't necessarily illegal or against code, they just push the perceived risk of the building past the surveyors acceptable risk.

Banks, being horribly risk-adverse made an EWS-1 a requirement for loans on buildings over 18 meters.

Somebody in Parliament said something along the lines of "All buildings should be safe". Banks then started making the EWS-1 a requirement for all loans of multi-tenant dwellings.

But someone is always responsible for ensuring a building is 'safe'. A poor EWS-1 result means someone has to make it safe. This someone is generally the buildings Management Company, or the Freeholder (who is entitled to recover those costs from the leaseholders).