His Ongar patch is on the outskirts of London, touching the M25 where the suburbs give way to rolling countryside. Nearby is Epping Forest, with its deer and assorted wildlife.
Yet for all its beauty, the area is a prime target for Londoners keen on blood sports. This time of year is particularly busy. With the corn just cut, parties will come out for a spot of hare coursing through the newly shorn fields and the badger baiters get down to work.
Sgt Ellis is acknowledged as a leading police wildlife expert, and now shares his experience with the eight wildlife officers newly appointed by the neighbouring Metropolitan Police.
His time is divided between tackling street crime and rural felonies. It is arguable which is more perilous. Drug addicts may carry guns and knives, but poachers often carry even heavier artillery.
'These are nasty, very violent people, often of the criminal fraternity,' says Sgt Ellis. 'We have to be very careful.' Once he confronted a poacher, who was armed with a .243 rifle, while he had only a stick in his hand. The police have had to use armed officers to tackle gangs on occasions.
Although all forces have a responsibility to take action under the 1981 Wildlife and Countryside Act, and many have started to appoint wildlife officers, Essex was one of the first to take it seriously. Sgt Ellis was appointed two years ago and has dealt with valuable missing tortoises and the illegal removal of bats from buildings.
The Metropolitan force has handled about 70 cases since December, but the number is growing all the time. According to Andy Fisher, the Met's wildlife liaison officer, appointed in January 1993, badger baiting sometimes takes place in London living rooms. Recently, City yuppies have been attracted to the 'sport'. They even video the fight to replay later.
'It's something which is becoming more and more of a problem to us,' he said. 'There does seem to be an increase in wildlife crimes.'
Essex farmers are terrified of putting up a fight. 'We are born again cowards,' said one, who wanted to remain anonymous. Just last week someone knocked at his door asking permission to run dogs over a freshly harvested field, chasing hares. He refused, but the stranger went ahead anyway, knowing there was little chance of being challenged.
Once the hares smell the dogs they run for their lives, the dogs giving chase. The men will walk out in a line, combing the field, letting their dogs go once the hare is spotted.
Badger baiting has been illegal since 1835. Bets of up to pounds 30,000 have been placed on which dog will succeed in killing a badger. This time of year badgers are particularly aggressive, putting up a strong fight to protect their young.
Badgers are also removed from setts and taken to secret locations - sometimes warehouses in London - to fight. The badger will be chained to a stake and dogs set on it. Live badgers sell for up to pounds 200.
On his patrols, Sgt Ellis looks for evidence of where setts may have been interfered with. Tell-tale signs include twigs sitting horizontally over an opening which, if moved, indicates to baiters that a sett is in use.
When he knows one may be in danger, he keeps a regular watch for signs of disturbance and may mount an operation to catch the gang.
A real townie - Tony Ellis was brought up in Romford and spent his early police career in South Ockendon - he found himself at a loss when promoted to Epping some 15 years ago.
He then began to realise there was an enormous problem with poaching although, at first, gamekeepers were reluctant to admit to an apparent failure in their duties.
He gained their confidence and started Keeper Watch - a network of gamekeepers who kept him informed of anything suspicious on their estates. It soon developed into a regular newsletter.
In the past five years, it has grown, with the local badger watch society, a group of people concerned about swans, and even the local council concerned over fly tipping - all wanting to use his network.
'When you've got as many as 500 people out there looking, you drag in a lot of information. People know if they come to Ongar we will deal with them,' says Sgt. Ellis. Now, he says, the problem is shifting further north, to Saffron Walden.
The network has helped the police with other crimes. Clive Bell is a gamekeeper on a 2,000 acre estate on the Essex/Hertfordshire borders.
He alerted police to people on his land who he thought might be poachers. One couple turned out to be drug dealers, whom the police caught red handed preparing drugs for sale.
In another case, an elderly man was found with a nine-year-old girl. There was insufficient evidence for a prosecution but social services became involved.
Tony Ellis believes pubs around Epping are still used for arranging dog fights, and possibly for holding them, too. Deer are also a target for poachers, carcasses selling for up to pounds 100 in the capital.
A week ago Sgt Ellis found signs that two deer had been taken out by a poacher, who had dragged the animals to a van and bled them in nearby undergrowth.
His most traumatic experience was coming across a roe deer in a poacher's snare, obviously near death with a gangrenous leg. Beside her a young deer looked on.
However, Sgt Ellis tries not to get into arguments about ethics. 'As far as I am concerned, if 300 pheasants are in a pen on private property and someone steals them, that is theft.
'People are stealing pounds 3,000 to pounds 4,000 worth of property.
It's not my job to think whether shooting pheasants is right or wrong, my job is to police this area. It's killing for the sake of killing I can't deal with.'
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