The term has been supplanted in the UK
What used to be called "beyond reasonable doubt" has been replaced with an instruction that the jury must "be satisfied so that they are sure before
they can convict." However, "No particular form of words is essential."
It is unwise to elaborate on the standard of proof: Ching (supra),
although if an advocate has referred to ‘beyond reasonable doubt’, the jury should be told that this means the same thing as being sure.
Crown Court Compendium Part 1 Chapter 5 p. 5-1 (92)
The new terminology was introduced in the 2010 amendment, and each subsequent amendment has further marginalised the old term introduced in 1935. Or rather, it was reinforced because the use of "sure" by judges has always been commonplace, and there has never been a requirement to say anything in particular, including "beyond reasonable doubt", a fact that was definitively decided in 1949.
It is felt that using "beyond reasonable doubt" and then explaining what it meant was more likely to confuse the jury's minds than to clarify them.
australia chose a different route; they use the term but don't explain it - explaining it beyond "the words mean exactly what they say — proof beyond reasonable doubt" can lead to the verdict being overturned on appeal.