In the doghouse!

Hector has well and truly blotted his copybook this evening. We took a last walk in the fine drizzle and found friend, Sammy, playing ball on the green with his owner. So naturally, I allowed Hector to join in with permission. After a good run round and lots of seal-like barking from Hector chasing Sammy, he spied his arch-enemy, Patch, approaching. As Hector was off-lead and Patch was on the lead, Hector flew at him and there was a real contretemps.
I have never seen Hector do this before. He hates Patch with a vengeance. I don't know why. Patch has done nothing to him. Whenever Patch walks past our house, Hector goes berserk. Patch is a large mature black terrier cross and much bigger than Hector.
Perhaps somebody's free-running days on the green are over!?
The photo shows Hector watching and waiting for A's arrival home.