Jim,
"2012.11.30. The burgers came from 6 plants in Ireland and 3 plants in the UK. The products which tested positive for equine DNA came from 2 plants in Ireland and one in the UK.
2012-12-07 Irish authorities become aware of the adulteration in ABP Food Group burgers with 29% horse meat content"
https://en.wikipedia.org/wiki/2013_horse_meat_scandal#UK_Investigations



That was the first finding of contaminated beef products. Soon it was found from elsewhere in EU