According to the Ark commissoning book on line here,
http://www.axfordsabode.org.uk/pdf-docs/arkroy27.pdf
last hook on was Gannet 044 "
piloted by Lt Slade with Lt Cdr Rotherham and Lt Cass in the rear." on the 18th November 1978, last launch was 27th November, "at 1511 when Phantom 012 crewed by Flt Lt M Macleod and Lt D McCallum was sent down the waist catapult and that was it."