I have been seeing this mistake for more than a decade. I and Irfan Anwar, son of the Music Director Khurshid Anwar have been correcting it forever :)
It is about the song, 'Ari O Mohe Cheed Gayaa' from Singar (1949). It shows Cuckoo and a male dancer. Since the name of Prem Dhawan is mentioned as a dancer in the credits, people claim that it is Prem Dhawan. It is NOT. It is actually Suryakumar or Robert Master, whose first film it was. He later became a famous Choreographer, sometimes dancing, eg, in Mr and Mrs 55, Barish, Nau Do Gyarah.
Here with Cuckoo in the above song.
OK, so what about Prem Dhawan? He shows up in a dance number soon after the birth of a child is announced.
Here in the front (right) with Hoor Bano (left) as the main dancer.
Suryakumar's filmography can be seen in Upendra's book on Group Dancers.
This was the first film of Prem Dhawan as a dancer, he had written lyrics for three films earlier.
Now You Know!