The officers were not in uniform and they had no police powers but their knowledge was there to be tapped into by local police officers.
The officers, along with the PSNI in general, were paying attention to all aspects of the Fair but in particular they had an interest in the way horses were being treated.

The Fairhill Street area of Ballycastle is popular with horse owners and several people from the south of Ireland - including the Traveller community - attend the Fair with horses.
And this year as well as the involvement of the Garda, Department of Regional Development officers were working with Moyle police to monitor the welfare of the horses.

Efforts were being made to ensure horses were not being tethered incorrectly or being left without drinking water.
Garda Sergeant Larry Brady from the Bridewell Station in Dublin, was joined by Garda Niall o'Connor from Tallaght Station, also in Dublin, at the Fair on Monday.

Sergeant Brady told the Times: "This visit is part of the Patten exchange programme. I'm here for eight weeks in H District and essentially whilst I'm here I'm to observe police operations and what I can learn and what I can bring too."

Monday was the start of his fifth week and already he has been out on patrol in Coleraine, Ballymena and Ballymoney.
He said the exchanges are without police powers but he said it is believed eventually the cross-border link-ups will lead to secondment with powers in both jurisdictions for the Garda and the PSNI.

He said: "The reaction from the public has been very positive. I have been out at public order incidents and been at a District Policing Partnership meeting in Cushendall. The reaction has been universally good and impressively there has been no bad stuff."

He added: "My experience with the PSNI has been hugely positive. There is excellent camaraderie. I have been welcomed and treated well here and I expect the next four weeks to be the same."
Sergeant Brady is due to visit Rathlin Island and District Policing Partnership meetings in Ballymoney and Ballymena.

He added that one of the areas he takes an interest in Dublin is policing of the monthly Smithfield Fair where horse owners gather and he was hoping to bring that knowledge to the Lammas Fair.
The Guards said that during their time at the Fair they would be using their knowledge of horse cruelty cases.

The officers were welcomed to Ballycastle by the Moyle and Ballymoney PSNI area commander, Chief Inspector David Wallace.
He told the Times: "We really welcome the opportunity to work alongside our colleagues. We hope to learn from them and hopefully they will learn from us. A number of our officers are working with the Guards over the border as part of this exchange programme.

"It is only positive when two neighbouring organisations can work with each other."