I think some of the most popular songs of Shamshad were composed by O.P. Nayyar (besides Naushad). I really love Shamshad/Nayyar and Geeta/Nayyar combo. O.P.Nayyar was one of the very few music directors who admitted that Shamshad played major part in establishing Nayyar's career. Nayyar mentioned Shamshad in many of his interviews.
1. He mentioned that it was bcoz of "Kabhi aar kabhi paar" that people started to recognize me.
2. He described Shamshad's voice as that of a "temple bell" for its clarity of tone.
3. He also mentioned that Geeta Dutt and Shamshad Begum were the ONLY singers who gave 100% to my songs. Rafi and Asha gave only 40%.
4. He also mentioned that Shamshad Begum was the best singer of his time and how she nursed a grudge against him because he never gave her a good enough break once he teamed up with Asha.
In Raju Bharatan Book it is mentioned that how Shamshad helped Nayyar during the difficult times of Mehbooba (1954). I dont remember the full story but it was something like all other Music Directors + Lata teamed up against Nayyar when Nayyar signed this film (which was left incomplete by Roshan). At that time all other female singers shyed away from singing for Nayyar. Nayyar went to Shamshad and said Appa Ji, if you dont sing for me now, I will be in ruins. And Shamshad said, Bring your songs and I will sing each and everyone of your songs. Mehbooba remains the only film where Lata and Nayyar shared credits on screen. After helping and establishing Nayyar so much, Shamshad mentioned that Nayyar also started to give her raw deals and sided with Asha. Shamshad mentioned how the happy version of "Leke pehla pehla pyar" was given to her, but the sad and the better version was given to Asha, but it was her (Shamshad) version that remains popular even today.
Nayyar used Shamshad as a primary singer in Mehbooba, Naya Andaz and gave her atleast one song in almost all his early films. Nayyar used Shamshad's voice in Chham Chamma Chaam, Aar Paar, Mangu, Naya Dour, Naya Andaz, CID, Shrimati 420, Howrah Bridge, Do Ustaad, 12-o-Clock, Mehbooba, Kismet, Qaidi, Mr and Mrs 55 etc.
It would be nice if somone can make a complete list of Shamshad songs for Nayyar.