The z9919 cluster is a relatively large genetic cluster with at least 300 members so far, well-known for their characteristic 459=9-9, YCA=19-19 pattern (double 9s at the 459 marker, and double 19s at the YCAII marker).
For those interesting this is the 9919 and RecLOH Project under Family Tree. I joined as it will help with our project as well. I see some interesting data developing around this haplogroup. I think we are dealing with an indigenous Celtic tribal group located initially in central Scotland, from the Firth of Clyde east to Dundee area.
I will post news on this as it comes in.