I find this interesting. The government seem to be encouraging more older people to 'return' to the workplace. However, I wonder how many of the people who may have taken 'early retirement' are actually working.
For example, I took 'early retirement' from my role eight years ago. The professional pension I received was miniscule, because I had not been paying into the scheme for very long. Therefore, I looked for work that I could do from home, so I could undertake caring responsibilities, but still work. That is when I entered the 'gig' (or freelance) economy and the casual workforce.
In these sectors (casual or freelance) there are many older people. In fact, I would say, there are primarily older people. The work is insecure (but often plentiful), and you tend to be treated a little like an afterthought. However, it is often flexible and can be varied.
I really do not believe there are large numbers of economically inactive older people. Rather, I think a huge swathe of older people have found they can use their skills and experience working online, and the flexibility of some kinds of online working enables them to undertake their caring roles.
The ageism that seems to be raising its head in the traditional workplace, may have arisen because older people may now be a minority in such environments.