Posted: 26/12/2012 at 14:12
My guess is that they're an autumn fruiting variety (as you say they're not overly tall they may well be Autumn Bliss). They fruit on canes produced earlier in the same year and they're simple to prune as you just cut them back to a shoot near/at ground level as soon as they've fnished fruiting. It's a little late to do it now but no matter, cut them back and mulch with some compost and new shoots will appear in the spring and bear fruit for you in the autumn.
If by any chance they are summer fruiting then the old canes should've been cut out after fruiting and the new canes that were already growing should've been tied in to grow on through the autumn - they will bear fruit next summer. If they are summer fruiting cutting them back now will lose your next summer's crop, but from your description I'm pretty sure they're autumn fruiting.