Although they each had hits as solo artists, this was the only UK #1 for Paige and Dickson. Paige had previously starred in Evita and Dickson was a former folk singer.

The song is from the musical Chess. It was written by Tim Rice with Benny Andersson and Bjorn Ulvaeus from Abba. It gave Benny and Bjorn their 10th #1 as writers.

Chess took two years to write. Bjorn said, "We were very pleased as we had something longer to work on, both the bigger format and the concept of drama and music together. I can see now that there is quite a lot of that in the later Abba songs, so we were working towards that. "One Night In Bangkok" and "I Know Him So Well" could well have been Abba songs. We had Elaine Paige in mind from the start. She was with Tim at the time and she was the best theater singer in the world. When we heard Barbara Dickson, we realized that she was wonderful too. She retained that folksy quality even when she did Chess and that really attracted me."

Barbara Dickson recalls, "It sounded to the average person in the street like a fantastic new Abba record and they loved the chance of buying an Abba record again. It was a sophisticated song- two women singing different things about the same man. We didn't record it together. Elaine had been to Stockholm and done the recording and I was brought in much later. When the record came out, we promoted it together of course." (Both the above quotes are taken from 1000 UK #1 Hits by Jon Kutner and Spencer Leigh.

This is the all time best selling song for a female duo in the UK.

The song has reached the UK Top 20 on two further occasions. In 2001 it featured on the double A-side of the last ever Steps single, reaching #5 as the flip to "Words Are Not Enough." Ten years later, a cover by Susan Boyle and comedian Peter Kay recorded for Comic Relief peaked at #11.