Hello Wim
That could simply have been a dirt strip down by the gun lines as they were on forward observation duties.
See
http://www.royalartilleryunitsnether...-squadron.html
Although this link does not mention geel it will give you an idea of what they were doing during the period that they were operational in western Europe following D-Day.
You can find quite a few other websites giving information on 658 Squadron on Google as well as the one that I have given above.
Hope this helps
Allan