The paint code for my 1999 +4 is Morgan Indigo Blue 0088.
On the small tin I managed to get hold of 8 years ago, it gives the paint manufacturer as Nexa, and the paint product as Belco.
Hope this helps.

Sid

Ex 2014 3.7 Roadster in Ferrari Le Mans Blue
Ex Indigo Blue '99 +4
Ex MogMMX Innovations winner