Martin
The most easiest way of finding his missions - as it is my intention eventually - is to locate the Operational Record Book of his squadron(s). As Gielstrup is normally told to have been shot down in one of his first missions, this might be fairly easy - AIR 27/2110 for a few months in the summer of 1943. Given the new copying charges at NA easy, but expensive...
I am not sure when he was actually posted to this squadron, if he trained in Canada until February 1943, and I guess he returned to an OTU. This would not have left much time for operational duty. Please refer to
http://www.danishww2pilots.dk/profil...?alpha=g&id=28
I a curious as to your reference to P8088.
Hope to help
Mikkel Plannthin