HG Capital's press release about the sale has this to say about its period of ownership:
During that time the firm supported Boosey & Hawkes’ management in executing
a transformation from a traditional classical music publisher into a 21st
century music rights group. It has outsourced a number of non-core activities
such as printing and distribution and developed a series of new revenue streams.
In particular it has developed a strong presence in the market for music in
advertising and film, where revenues are currently growing at approximately 30%
Here's Daniel Wolf on the changing relationship between composer and publisher. My own experience dealing with all levels of music publishing suggests to me that an outfit such as Frog Peak can be a very effective way for composers to pool resources, while self-publishing composers vary in their effectiveness, from someone like Christopher Fox, who runs a very effective cottage industry, to the Stockhausen verlag, which, surprisingly for the imprint of a composer who was so much at the forefront of technology, doesn't even take credit cards. Meanwhile, the big old publishing houses seem to expend more effort in restricting access to their music than promoting it.