Sounding very much like The Hollies, this is Marmalade. The song was written by their lead guitarist Junior Campbell and singer Dean Ford (credited to his birth name, Thomas McAleese).
The song went on to chart worldwide, reaching #3 in the UK in 1969, #10 in the US in 1970 on the Billboard Hot 100, and #7 on the Cash Box Top 100. Initial sales were significant in both countries, and the one million mark was reported in November 1971, when the group was presented with a gold disc for global sales.