Statutory Periodic Tenancies - notice period by tenant.

Tenancy Types and Management

If the tenant is on a rolling monthly Statutory Periodic Tenancy (SPT), they are supposed to give 1 months notice to the landlord of their decision to quit.

Does the 1 month notice have to run from a rent day?

For example, say the next rent day is 25th March and they give notice today (12th March), what is their legal position. Can they leave on the 12th April or the 25th April.

I realise that the landlord can now use a Section 21(1)(b) after the Spencer v Taylor court action decision and not put it on a rent day, provided the landlord give at least 2 months notice. Are people aware of this?

And has this any implications on the tenant providing notice in an SPT.