Groin pain 15 miles in - incorrect saddle position?

[pincher]

Firstly, let me make clear the fact that I'm unfit and am usually knackered after about 20-something miles but I was wondering if I need to need to maybe move my saddle back a bit along the horizontal (am happy with the height - I think!), as I tend to get a slight twinge near the nether region after 15 miles or so. It isn't enough to make me stop but am aware that it is there.

Any suggestions?

Edited to add that the bike is a hybrid (Spesh Sirrus Sport)

Edited by pincher on Saturday 27th April 17:52