Why would it not work? Have you tried it yet? Private keys are ALL derivated in the same way, so it wouldn't matter if it is created in a wallet X 10 years ago, or in wallet Y 10 minutes ago.
Do make sure you're using the right electron cash, and that you're not running a scam wallet, (check the signatures of your download etc.) Otherwise all of your bitcoin cash AND bitcoin might be lost.
Thanks AdolfinWolf. No, I have not tried it yet. I made some stupid mistakes in the past and almost lost my bitcoin. That is why I want to make sure I don't make a similar mistake again.
The keys were generated with Multibit long ago. When I recently entered the keys into Electrum it gave me the message: Warning, imported keys can not be recovered using the seed! That gave me the idea that the keys must be generated by, and somehow connected to, Multibit. And when I would enter the seed into Electron Cash, it would not see the imported keys. Does my reasoning make sense?
I could simply try it, if you think nothing bad will happen. I hope you understand why I am being very careful here, I got my bitcoin back and don' t want to jeopardise that again.

Is Electron Cash dedicated to Bitcoin Cash only? Can it in no way interfere with my bitcoin BTC?