Simon Fleming, 1st Baron Slane

Simon Fleming (died 1370) is the first Baron Slane whose holding of the title can be conclusively established.

Archembald's grandson, Archembald fitz Stephen le Fleming, came to Ireland with King Henry II of England in 1171 and participated in Hugh de Lacy's plantation of the Kingdom of Mide.

He spent much of his time in England, and acquired extensive lands in Devon and Cornwall (he was related by marriage to a number of prominent families in those counties, notably the Bassets and Champernownes).

In 1363–64 he was a prominent member of the "reform party", which campaigned against the widespread corruption and maladministration of the Irish Government: he was part of a powerful delegation sent by the Irish House of Commons to England to outline their grievances, and King Edward III appointed him to a royal commission to consider what reforms to government were necessary.

The reform party had some success: in particular, they secured the removal from office, for a time, of Thomas de Burley, the notoriously corrupt Lord Chancellor of Ireland.