Will the UK go back to the Pound and shilling monetary system?
Its kind of irelevent now anyway. A pound in 2021 basically has the same purchasing power as a shilling in 1970 just before decimalisation. The 10p coin (which was worth two shillings at the time of decimilisation) is about the lowest useful value coin you have (its been a long time since you could buy any single item with a 1p, 2p or even 5p coin).
What would be the point in subdividing 5p or 10p into 12 or 24 old pennies?