For info - an EC225 has just lifted off the Sedco 704 en route for Aberdeen at 0840 local time.
This a/c had been shut down offshore since the 14th due to a tech problem. Another EC225 will be lifting from ABZ shortly to fly to the S704, there may be one or two other flights this morning before the ash cloud returns this afternoon
Edit - there are now 5 North Sea helicopters airborne in the Central area at 0930 local.