The ATPL has no inbuilt IMC privileges.
The reference is to a UK National ATPL which has inbuilt privileges:
ANO Schedule 7
Privileges:
The holder of an Airline Transport Pilot's Licence (Aeroplanes) is entitled to exercise the
privileges of a United Kingdom Commercial Pilot's Licence (Aeroplanes) except that the
restriction at sub-paragraph (4)(f) of those privileges does not apply.
Privileges:
(1) The holder of a Commercial Pilot's Licence (Aeroplanes) is entitled to exercise the
privileges of a United Kingdom Private Pilot's Licence (Aeroplanes) which includes an
instrument meteorological conditions rating (aeroplanes) and a night rating
(aeroplanes) or night qualification (aeroplane).