Thanks for your replies.
I found out today that under the terms of the 1986 Al Yamama agreement, service is reckonable and pension is unaffected (yippee)
...........................but as Impiger suggested other secondments and loans do affect your service and pension and you may have to "buy back" the appropriate time to ensure you get the pension you thought you would.
JSP 468 I think is the oracle or was it 486???
Cheers I66