George Merrill and Shannon Rubicam wrote two US number one hits for Whitney Houston in the 1980s.

The couple had moved from Seattle to California to work as songwriters. How Will I Know and I Wanna Dance with Somebody were the songs that made their names.

By 1988, they had their own record deal and scored a global hit of their own with the song Waiting for a Star to Fall, recorded under the name Boy Meets Girl.

The duo told the BBC about how their songs came to be part of Whitney Houston's repertoire, and how her vocals embellished their original demos.

George: We'd had success prior to How Will I Know, but nothing that compared. That was the meteoric rise, right there. But it was originally written for Janet Jackson.

Shannon: We were asked by our publishing company to write something for Janet's album, and we just wrote for what we knew of Janet's voice and style. But she took such a different musical direction on that record, which became her Control album, that they turned down our song.

But then Clive [Davis - Arista Records] heard it and wanted it for Whitney, who he had discovered.

George: We didn't know much about Whitney. There was a buzz. People who had heard her and seen her were excited. But we were concerned it wouldn't work out as well as it might have with Janet Jackson.

Then we got a call from our friends Alan and Preston Glass [record producers], who were in the studio in San Rafael, northern California with Narada Michael Walden [producer of How Will I Know].

They were kind of excited and whispering, "I think you've got to hear this right now". They hit playback and we got a chance to hear How Will I Know in its rough, unmixed form.

Shannon: Even down the telephone, I'd never heard anyone sing like that. Especially on one of our songs. I think our hair blew back!

George: She bit off those lines and chewed up the song. It was so exciting.

Shannon: The demo recording had been very soft and sweet, because we were thinking of Janet Jackson. Whitney added her power punch to it.

I'd put a few ad libs in on the guide vocal track, but she embellished them and made them her own. She sang the hell out of it.

George: When we came to write I Wanna Dance, that was written specifically for Whitney. And it was really exciting to hear some of the little things Shannon did on the demo, little twists on the words, when Whitney picked those up and sang them later.

Shannon: But she was always very true to the melody. She had the sensibility to embellish the song with acrobatic licks but maintain a real elegant control. She never got crazy. It was really something.

If you listen to the a capella version of How Will I Know, she's so precise. Even at the lower end of her zenith, she still was one of the better singers around. Most of us could never approach that.

Her impact on the world of female singers, in particular, was so strong. It's strange to think there's a group of girls aged 10 and 11 now who'll grow up with a completely different set of idols, and they won't know about Whitney Houston.

George: For me, the other memory that sticks out was when she was playing at the Greek Theater in the open air in Los Angeles [on the 1986 Greatest Love Tour]. Shannon and I had seats right back by the mixing board and when she sang our song, everyone jumped up. She was so powerful and it was such a great moment.

We got the chance to meet her afterwards. She was just this kid - this elated kid.

Shannon: Effervescent and silly and happy. Her parents were there...

George: ...and they were hugging her. Everyone was hugging. It was a really exciting moment.

Shannon: The gifts that she brought into our lives were so unexpected and so brilliant. I will always be grateful to her for that.