Want another s.21 problem with which to grapple?
See s.75(1) of Housing Act 2004. "No section 21 Notice may be given in relation to [an AST] of a part of an unlicensed HMO so long as it remains such an HMO."
At least the provision is clear. Just as where a deposit should be protected but remains unprotected, when no s.21 Notice can be served, the same is true where a property should be licensed as an HMO but remains unlicensed.