Why is Fernando Alonso back in F1?

2021 has seen a decent-sized churn of drivers through F1’s off-season. We have three rookies stepping up to the pinnacle of motorsport, with Haas and Red Bull casting aside four drivers between them. But three into four leaves a balance of one. One more space for an up-and-coming driver who can show the world what they’re made of and make a name for themselves? Erm, not quite. Instead, we see the return of a driver who turns 40…