Trove is invaluable for earlier material, but not later years of the Sydney Morning Herald
The Sydney Morning Herald archive is here.
https://archives.smh.com.au/
You can have 24 hours access to the item (and the whole archive) for AUD15. There are rates for longer subscriptions.
Their 8 October 1964 snippet transcription has: McGREGOR – The Relatives and Friends of the late JOHN ANDREW MCGREGOR, of 2(34 Dellview Street, Bondi…
https://familyhistory.bdm.nsw.gov.au/lifelink/familyhistory/search?1 has the NSW births deaths and marriages indexes.
From the deaths index:
MCGREGOR JOHN ANDREW
Registration Number: 5272/1964
Father’s given name: ANDREW WALKER
Mother’s given name: MARY
District: SYDNEY
By refining the search date range, you find the death was 6 October 1964.
You can receive the registration details by email for AUD 39!
An other family history source is the Ryerson index to Australian death notices:
https://ryersonindex.org/search.php
It has some of the same details, slightly different to what you already have, and a different publication date (by I can't find for that date).
Many thanks to all who replied. It is the correct one and I found the link on Ancestry initially but don't subscribe to the newspaper part of the site. His mother was Mary, Terry so that helps confirming it is the one I thought it was. His father was Andrew but he deserted his Australian family to come back to the UK.
Lyn