In the absence of an answer thus far, I have removed the calendar/datepicker function from the form completely using the following solution by "intrepid" on July 20th 2020.
1) Edit view.js file and comment out this line :
var current_datepick = '#' + $(this).attr("id").slice(0,-1) + 'datepick';
2) And add to your theme's css:
IMG.datepick-trigger {display: none;}
I can verify that this works a treat, leaving the form user to fill in the date correctly.