Yes, and the same for 'fish' and 'wish' too. One of the great benefits of having a highly consistent language like English is that these rules are 100% reliable.
'Astonishing' was actually a deliberate policy of post-war governments, and formed part of the overall strategy known as 'maudling'. The Thatcher government, of course, declared that 'astonishing' was old hat and Britain was now in the 'Steven age'. Thus the Villa knell was sounded.