Thanks for the quick response.
Yes it is set up in the payment module as I want it. When the problem first appeared, as a diagnostic measure, I tried using the payment method to turn off the express button in the checkout view and turn it on in the shopping cart instead. It duly appeared in the cart (where it works as it should), however, when I reverted to the desired setup, the button did not reappear in the checkout. I've cleared the cache (on the browser it's not enabled on the site) and the cookies, I've tried different browsers....
In addition, I've looked at the html to check the button wasn't actually there but perhaps out of view due to a CSS snafu but it's not present. I deleted and remade the payment method, changed the order of payment methods, reinstalled the hikashop plugin all to no avail. It works on other sites I have which I have not yet upgraded, perhaps I should back one up and upgrade to 2.3.5 to see if something similar happens?
Any other ideas?
Alan