As some others have mentioned - I'd call your bank to make the transfer. Just over a week ago I attempted to transfer a rather small (in comparison figure) £5k to someone for a car. Immediately flagged as potential fraud, First Direct's anti-fraud people immediately called.
Got asked the most bizarre questions - so I failed security checks and had to contact their Customer Service to get everything moving. I did this - was told all was well, transfer back on. Money still hadn't arrived 2hrs later, contacted FD again, told everything was OK, called again later the same day, called the following morning to the question "Oh, didn't the CS staff tell you yesterday the transfer was cancelled and you'll have to initiate it again?"
Just make your life easier - call them and do the transfer with the over the phone so you pass security there and then.