Hmmm.... Well I've just been given more information on the parents which would rule out the option of a Killer Bee.

Sire: Killer Bee (Spider Super Pastel)
Dame: Pastel Super Butter

This would only give 4 possible outcomes:

Butter Pastel
Bumble Bee Butter (Queen Bee)
Butter Super Pastel
Killer Queen Bee (Butter Spider Super Pastel)

So this leaves me thinking that this is either a darker than usual Killer Queen Bee, or possibly a Queen Bee. Opinions?