[DTV]

You don’t need to explain what the Chancellor is

The German chancellor is always referred to as such, never “The German prime minister known as the chancellor, not to be confused with our definition of a chancellor, today announced…”

I don't really think it's plausible to claim that the German Chancellor and the Chancellor of the Exchequer are of equivalent international recognition. For whatever reason, it is widely accepted in the English-speaking world that Germany's head of government is referred to as the Chancellor rather than the standardised Prime Minister (a courtesy not extended to other non-standard equivalents like Italy's President of the Council of Ministers or Spain's President of the Government). I don't think the same is true of the British finance minister, especially considering that other English-speaking countries have a variety of terms for their equivalent.

A three word nudge during the introduction of a story is, at worst, going to mean nothing to viewers, while potentially aiding the understanding of many more.