The payment actually arrived Thursday 27 August from The Currency Cloud.
It turns out that, according to Linked In, Vladyslav is the CTO of Revolut.
If you're on a different phone, or on an i Pad or i Pod touch, you might want to use a different number to set up mobile phone billing.
As a next experiment I tried to transfer the £1 back to my bank account.This raised an error message, so I contacted Revolut support again, using twitter.They tweeted a reply announcing both an update fixing the SMS problem (Note 3) and also asking me to contact "in-app support" regarding the error I got when trying to withdraw my £1.Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Other company and product names may be trademarks of their respective owners.Apple makes no representations regarding third-party website accuracy or reliability.
Here is a screenshot of my phone showing the "Withdraw button" that Nikolay mentioned in his email.