Checked with Transferwise this morning was told that my 1700 pounds would reach my bank here on Monday 1st June

The problem with slow transfers is generally as you pointed out.. weekends and holidays.. also the time it may take the receiving bank to process the transfer.. When you make a transfer you get a notice that they have taken the money and it is in the process of being moved to the receiving account..... after that it is out of their hands..