Here's a quote from Wet Labs website.

"The 15 Watt and 30 Watt sets were built for Matchless to their specs and never picked up  by Matchless from the manufacturer due to financial problems on their part. Their loss is your gain. The 15 watt set was used in the Spitfire, Lightning, and  Hurricane, Etc. The  30 watt set was used in the DC30, the SC30, and the John Jorgensen. They are drop in replacements for Matchless and VOX amps. They are designed for two EL84s (6BQ5s) or four EL84s respectively."

While Dave is a really nice guy, and sells a great transformer set, I don't believe this statment to be true.
I got a set last week with BLANK Transformer company's part number stickers still on them.  The OT was wound in 2011, The PT and Choke in 2010.
If they were in fact "left over" Matchless stock they would be made by (WTI) Wood Transformers, Inc. and would have date codes from the '90s. Right?

This is and opinion piece based on the information at hand and reasonable deduction and research. It is in no way to be taken as fact or meant to be harmful to any party in any way.