What is the reason behind the British naming Palestine as Palestine ?
The British did not come up with anything new. It was called the British mandate of Palestine, because the land has always been Palestine
The name Palestine is the most commonly used from the Late Bronze Age (from 1300 BC) onwards. The name is evident in countless histories,‘ Abbasid inscriptions from the province of Jund Filastin, Islamic numismatic evidence maps (including ‘world maps’ beginning with Classical Antiquity) and Philistine coins from the Iron Age and Antiquity, vast quantities of Umayyad and Abbasid Palestine coins bearing the mint name of Filastin. The manuscripts of medieval al‑Fustat (old Cairo) Genizah also referred to the Arab Muslim province of Filastin. From the Late Bronze Age onwards, the names used for the region, such as Djahi, Retenu and Cana’an, all gave way to the name Palestine.Throughout Classical and Late Antiquity, the name Palestine remained the most common. Furthermore, in the course of the Roman, Byzantine and Islamic periods the conception and political geography of Palestine acquired official administrative status.
Shocking isn’t it? Not really.