Tom Springfield, the songwriter best known for writing some of The Seekers' greatest hits and as the brother of singer Dusty, died last month aged 88 according to posts on their official Facebook pages.
The page for the late Dusty Springfield carried the news of his death on Saturday, but revealed he had actually died in London on July 27.
The post went on to explain that "being a very private person, the news [of his death] somehow went under the radar and has only now come to light now".
His passing came 10 days before that of Judith Durham, The Seekers' lead singer, who died on August 5.
In a post on The Seekers Facebook page, the surviving band members – Athol Guy, Keith Potger and Bruce Woodley – paid tribute to Tom.
"We have heard reports that Tom Springfield has died. Tom was our fifth Seeker and we could not have done it without him. He was our creative heart and soul. A truly gifted songwriter, guiding light and powerhouse".
Tom wrote The Seekers biggest hits Georgy Girl, The Carnival Is Over, I'll Never Find Another You and A World of Our Own, earning him the unofficial title of the "fifth Seeker".
Born Dionysius Patrick "Dion" O'Brien on July 2, 1934, he launched his music career performing with Dusty in the band The Springfields.
Five of the group's singles were UK Top 40 hits between 1961 and 1963, and two of them — Island of Dreams and Say I Won't Be There — reached No. 5 in the charts.
The Springfields broke up in 1963 when Dusty left to start a solo career.
Tom continued to write and became the principal songwriter for The Seekers.