If you have not already done it you might be interested in reading the draft client money protection regulations. The requirement to belong can be found here and the rules for the schemes can be found here.
Agents would be well advised to study this legislation as it contains some interesting provisions. For example, it comes into force on the 1 April 2019 and agents will have to pay any interest earned back to the owner of the client money, this may make insured deposit schemes much less attractive.
Scheme members will have to have a written procedure on client money and this will have to be displayed in the office and on the web site.
Not being a scheme member carries a maximum penalty of £30,000 and not displaying membership carries a maximum penalty of £5,000. The penalties can be used by the local authorities for general enforcement work in the private rented sector.