The code signing key used for BT747 had to be upgraded to SHA-256.
Unfortunately that also revoked the old key and apparently the timestamping was not properly done with the previous signatures. So the java laucher complains that the certificate is revoked.
All files have been resigned and republished.
You may need to launch:
[on windows : "Windows Key + R" to access the execute popup where you can enter this].
Then, right click on the BT747 application and do "Launch online" (Exécuter en ligne) - you can also create the shortcuts from here if you are missing them:
Sorry for the inconvienience, you can blame Microsoft for it - they require SHA-256 signatures instead of SHA-128 signatures and the code signing certificate was delivered a few years back with a SHA-128 signature.
The benefit is that the timestamp now really is in the signature ;-).