Possible Clues:

• Horse with excellent name -- Ben, maybe?
• Eg Ben’s horse, popular around area
• Natural elevation of the earth's surface
• Large stock surplus
• Large surplus stock
• Huge quantity swirling in a tum, no?
• Horse at home eating a huge quantity
• Odd man out in high position
• Horse ain't missing top of tail in Blackstairs
• Open University set of books dumped in sea -- great quantity