It is a selection of L. cotyledon, named for the late stalwart of the SRGC, the marvelous Joyce Halley, who was the mainstay of the Seed Exchange for many years.
There are only two mentions in the SRGC journal, both of plants of this form being shown in Aberdeen by Mike Hopkin. From Mike's plants, and Carol's, shown above, we can see what a good form it is - but I cannot find who named it- I have a suspicion it may have been Ian the Christie kind....... 
Yes, it is confirmed - this lovely plant was selected and named in honour of Joyce by Ian Christie .
