Lagunette was a full-sister of The Oaks winner La Lagune, being the last of four foals produced by the unraced broodmare Landerinette.
The filly was then dropped back in distance and moved up sharply in class for the Group One Prix de Diane over 2100 metres at Chantilly Racecourse on 13 June.
Pawneese, who had won the King George VI and Queen Elizabeth Stakes in July, started the odds-on favourite ahead of Riverqueen, with Lagunette, ridden as usual by Paquet, next in the betting on 14/1 in a ten-runner field which also included Sarah Siddons and Theia.
Lagunette took the lead in the straight before being headed by Sarah Siddons inside the last 200 metres but rallied to defeat the Irish-trained filly by a nose after what Timeform described as a "tremendous battle".
The independent Timeform organisation awarded Lagunette a rating of 122 in 1976,[3] making her nine pounds inferior to their top-rated three-year-old filly Pawneese.
Data Traffic, a chestnut colt sired by Irish River, had a successful turf career winning seven races out of 41 starts.
[8] Safety Feature, an unraced bay filly foaled in 1985, sired by Be My Guest[9] produced several minor winners including Trade Dispute, who won fourteen race between 1995 and 2003.