Well, I would think it is difficult to justify lots of new buses everywhere since as you say they are almost empty except at rush hour. However, in London, buses are an essential part of the system ... and because of vandalism and 1-driver operation, installing cameras also seems to be essential.
With TGP rushing £4.6m into the 75% purchase of 21st Century, they must be pretty certain all their money can be recouped within 2-3 years, since 3-4 years is usually the max timeframe for new-venture investments. We'll see. It's extremely rare for a company to invest 60% of their market cap in a single year... so TGP are hell-bent on something.... let's hope it's not a Langbar-style pot of gold LOL