what about if it's wildlife on your own property?

It's hunting when you go out and command the dog to do it. How they'd prove or disprove intent if you were caught, I'm not sure - obviously someone caught with a weapon to "dispatch" of any animals caught and a herd of dogs (especially breeds typically used for hunting) at an unsociable hour is probably going to be more likely to be suspected than a family with a ball chucker and their slightly tubby Labrador who's suddenly decided to make a run after a deer on their Sunday morning walk.

There's a few exemptions to the law on your own property/on property when given permission by the owners.
Apparently you can hunt rats, rabbits and hare, and you can flush out wild animals to allow a bird of prey to hunt them. Seems to be exemptions on hunting wild animals that have been released for captivity but there's several conditions you need to adhere to. And you can hunt out wild animals (on your own land) if you believe them to be injured and your intent is to stop their suffering, or if it's in connection to a study on that animal but again, several conditions to follow.

http://www.legislation.gov.uk/ukpga/2004/37

A couple of years ago I was walking with some friends on the South Downs. We had about 8 or 9 dogs of various breeds with us. One of the dogs suddenly shot off across a ploughed field & managed to catch a rabbit & kill it. She was on her way back to us with the dead rabbit in her mouth when over the hill behind her came a police range rover (countryside police I think).

Embarrassingly she calmly trotted along in front of the range rover which just followed her slowly along the track until she got to us & my friend put her dog on the lead. The police got out & explained that the farmer had reported instances of hare coursing on his land so the police were keeping a close eye. They had seen a group of people with lots of dogs so came to investigate. When they saw a load of middle-aged women with a motley collection of dogs, ranging from labs, to lurchers to GSDs, retrievers & very elderly JRTs, they just laughed . They said it wasn't a problem if the dogs caught the odd rabbit, in fact the fasrmer would probably be happy about that. It was only illegal hare coursing they were concerned about. But it did give us a scare in case we were doing something wrong!

My Border retrieves them regularly, and has dispatched them too.

My friends dog ran in to some woods and came back gently carrying a live rabbit, it obviously has mixi and her dog had no intention of harming it, when it dropped it the rabbit ran very slowly away so she allowed her lurcher to quickly dispatch it. Is that illegal?

Its not illegal to hunt, catch and kill rabbits with dogs at all.

Wow! That's a great set of photos!

The most Dahlia has done is chase.

Here she is on the release command (we set this up so I released her and my partner got photos).



And the ducks fly off!

Nice work well done!!

All mine are taught "leave" most important it is.

Yes! Leave is SO important. A lot of people here like to feed the ducks and geese so if there are people there a good "leave" command and she won't go chase. But if no one is there, she gets to walk up (slowly) and chase on command ("go get 'em!").