That sounds quite good for GPO!
The string accompaniment at the beginning of the piece that goes from E minor to D major could be dressed up a little for more interest. Try something like Emi sus4-Emi, D2-D. That little contrapuntal motion under the melody creates more interest.
I also think adding a solo woodwind to the string melody at the beginning, perhaps a clarinet the first time and an oboe on the repeat could be effective to create even more orchestral color shifts.
All in all, a very nice short piece!