Complex sentence: It had been kept at Vaynol Park as a semi-feral herd since 1872, but after the death of the owner, Sir Michael Duff, the estate was sold and the herd was moved to a farm park in 1980.
Split into simpler sentences: It had been kept at Vaynol Park as a semi-feral herd since 1872. After the death of the owner, Sir Michael Duff, the estate was sold and the herd was moved to a farm park in 1980.