Although I can be of no help in locating the 78 rpm recording of "Peter"
by The Ramblers, I can add that the leader of this band was Theo Uden
Marsman and their "in-house" singer was a chap called Max van Praag.

While still a pre-teen youngster living in Holland, I tried to never
miss one of their "live" radio broadcasts during the late 30's and
early 40's, when one could use a bit of joyful music during an
otherwise gloomy period.

Their repertoire contained, in addition to some cutesy songs,
many of the popular American tunes, when everything American was "cool"
and created in ones mind, at least in mine, the image of that far away
country where the streets of New York were paved with bricks of gold and
a boy could become a millionaire by selling newspapers on street corners.

To get even closer, all you had to do is buying a "Life" or "Saturday
Evening Post" magazine from the kiosk at the railway station, find a
quiet spot, look at the pictures and realistic or not, put yourself in
that frame of mind.  A boy was still allowed to dream...

And so The Ramblers were a connection even when Max, by the farthest
stretch of imagination, could not be measure up to an American crooner.
I would think that a CD may have been issued of their music including
"Peter", although I have no information that would confirm that.
Some of the Dutch contributors to MMD may be able to help in that regard.

Albert