I am looking for information about 2 early Britten pieces.  I cannot find
reference to them -anywhere-.  They are included on a new Erato CD 25502
(as usual I have only the catalog) and billed as 'world premieres'.  (It
looks nice, Nagano/Halle' Orch, Bashmet (va), Kremer (vn).) The works are:

Double Concerto for Violin, Viola & Orchestra (written at age 18)

2 Portraits for?Viola (plus other solo instrs?) & Orchestra

Is anyone familiar with either work (or both for that matter)? I have
exhausted all other resources, no list of works goes before Op. 1.
Any dates, correct forces, proper titles, etc.  would be useful.

Thanks,

Bob K.