OLIVIA NEWTON-JOHN
Till You Say You'll Be Mine
(Jackie DeShannon)
UK 1966

On Decca (UK), Olivia Newton-John's first single, recorded in London.

British-born but raised in Australia from the age of four or five, Olivia returned to the UK as a teenager in 1965 after winning the trip in a TV talent quest. She performed (but didn't record) with Australian singer Pat Carroll as Pat & Olivia. 

Pat returned to Australia when her work visa ran out, but Olivia stayed on in the UK and began what turned out to be a long and successful solo career, although her first Top 40 single wasn't until 1971, If Not For You (#35 UK, #25 USA).

See also The Banks Of The Ohio, one of her greatest hits.

Thanks to Martin Pardys for mentioning Pat & Olivia.
THE SEARCHERS
Till You Say You'll Be Mine
(Jackie DeShannon)
UK 1965

On LP Sounds Like Searchers and EP Four By Four.

The Searchers recorded both sides of the original Jackie DeShannon single. Their 1964 version of the other side, When You Walk In The Room, was a hit single for them (#3 UK, #35 USA).
THE FOURMOST
Till You Say You'll Be Mine
(Jackie DeShannon)
UK 1965

On album First and Fourmost by Liverpool band managed by Brian Epstein and produced by George Martin. Their first two singles, carrying Lennon-McCartney writer credits, were "songs The Beatles gave away", Hello Little Girl and I'm In Love.
SHIRLEY & JOHNNY
Till You Say You'll Be Mine
(Jackie DeShannon)
UK 1965

Single on Parlophone, B-side of Day Dreamin' Of You. The A-side was a Jackie DeShannon co-write with Sharon Sheeley. Arranged by Arthur Greenslade.

Johnny Wheeler was playing in his brother's skiffle band when he met Shirley Bagnall at a gig in High Wycombe in 1962. The duo was signed to EMI after auditioning for producer Ron Richards. They issued thirteen singles on Parlophone, Mercury and RCA, none of them a hit, but they appeared on a number of top British TV shows and were kept busy as a cabaret and cruise act before breaking up in 1974.

Further reading: Shirley & Johnny's website.
JACKIE DESHANNON
Till You Say You'll Be Mine
(Jackie DeShannon)
USA 1963
Original version

Single on Liberty, B-side of When You Walk In The Room. Both sides of the 45 were written by DeShannon, produced by Dick Glasser and arranged by Jack Nitzsche.

Singer-songwriter Jackie DeShannon (b.1941, Sharon Lee Myers) is best known for her own hits:

What The World Needs Now Is Love (Burt Bacharach-Hal David)
Jackie DeShannon 1965, #7 USA.
Put A Little Love In Your Heart (Jackie DeShannon-Randy Myers-Jimmy Holiday)
Jackie DeShannon 1969, #4 USA. Co-writer Randy Myers is Jackie's brother.

She also recorded the original version of:

Needles And Pins (Sonny Bono-Jack Nitzche):
Jackie DeShannon 1963, #83 USA
Better known by The Searchers 1964 (#1 UK, #13 USA).

Some of her own compositions - often in collaboration with Sharon Sheeley - have been known through other artists' recordings:

Dum Dum (DeShannon-Sheeley):
Brenda Lee 1961, #4 USA, #22 UK.
(He's) The Great Imposter (DeShannon-Sheeley):
The Fleetwoods 1961, #30 USA.
When You Walk In The Room (DeShannon-Sheeley):
The Searchers 1964, #3 UK, #35 USA.
DeShannon also recorded the original version (1963)
Don't Doubt Yourself, Babe (DeShannon):
The Byrds 1965, on album Mr Tambourine Man.
Come And Stay With Me (DeShannon):
Marianne Faithful 1965, #4 UK, #26 USA.
Bette Davis Eyes (Donna Weiss-Jackie DeShannon):
Kim Carnes 1981, #1 USA.
First released by Jackie DeShannon, 1974, on album New Arrangement.
Breakaway (DeShannon-Sheeley):
Tracey Ullman 1983, #4 UK.
First released by Irma Thomas, 1964, as Break-A-Way.

Further reading: 1. Jackie DeShannon's website. 2. Jackie DeShannon Appreciation Society. 3. AllMusic biography. 4. Sharon Sheeley at All Music and The Guardian (obituary). 5. Sharon Sheeley tribute at Rockabilly hall of fame.

Corrections or comments? Contact the writer.