The church's origins are medieval, though the present building was extensively remodeled during the Victorian and Edwardian years.

Isan died in 537 AD, so his time in the district would have been fleeting, but had significant effect.

[2] The first mention of a proper church at the location dates from the 12th century, at which time it was a chapel of ease to St Mary's Church in what was then the separate and fairly distant town of Cardiff, which would not absorb Llanishen until the late 19th century.

[4] In 1993, the Llanishen Local History Society planted a tree at the site of St Isan's original llan.

[5] Media related to St Isan's Church, Llanishen at Wikimedia Commons