Possible Clues:

• Source of trouble -- or likely help to an angler?
• One is fishing for something if one sees this as potential trouble
• Problem coming from wandering cows on farm
• Conservative was on form after diverting potential trouble
• Potentially embarrassing situation for woman working in Civil Service
• Fisherman holds on to them presumably to open up - there's more trouble to follow
• Contentious issue
• Those dropping a line might want them to open up - there's more trouble to follow
• Expression that ought to relate to "for the birds"
• Best not to open this farm — no cows unfortunately!