Very old Guardian cryptic crossword (UK) archive search

I am attempting to locate a very old crossword puzzle published in the UK newspaper The Guardian circa 1980.

The reason being my Father recently passed away and my Mum fondly told me a story of how when they first met she impressed him by completing the final clue in a cryptic crossword that was left out on the side.

The answer she filled in was EASTER ISLAND.

Basically I want to attempt to track down the puzzle and make a print out of it and frame it etc.

So my question is, is there an archive where I could even look? And also of course ideally be somehow able to scan by clue answer and narrow it down to puzzles containing that answer!