Found the issue. Somehow the shipping (custom configuration) had been tuned off on the dashboard, although not by me?!
S of two orders this morning , the orders have gone through without any shipping being offered. Also just noticing issues with autocomplete on the address field (Maybe related) (an issue with the API that offers this functionality perhaps?)
So we have altered nothing on our end…
Checkout process currently is just add to cart, enter payment address > (no shipping) > payment
The site in question is superclean-pw.co.uk