Apologies for the inconvenience: we allowed our “SSL Security Certificate” to lapse. It expired this week and it is now paid up again.
The certificate issued by the independent authority who validates our domain had just expired. While the encryption is the same, paying independent authorities for the certificate helps authenticate we are who we say we are. In other words, there never was a problem with security of information and everything is up to date and should be fine now without any warnings in your web browser.