Your electricity MPAN (Meter Point Administration Number) is the unique identifying electricity number for your property. Your MPAN is sometimes referred to as a S Number. It is unique to your property and does not change if you change supplier.
Your gas MPRN (Meter Point Reference Number) is the unique identifying gas number for your property. Your MPRN is sometimes referred to as a M Number. It is unique to your property and does not change if you change supplier.