Hello,

Once more to ask if this expression is an idiom and what it could mean.

After the couple has managed to put a swarm of bees into boxes, the lady says:

So, greatly relieved, with a feeling of Raiders Past, I went light-heartedly up to the farm to get some eggs.

I can’t find it on the internet; is it an actual idiom or something of the author’s own doing?

Thank you very much,
Ana

‘Raiders Past’ (also known as ‘All Clear’) was a term used in World War II, meaning that an air raid had finished and it was safe to go out again.  It was signalled by a continuous tone on an air-raid siren.

In the extract you quote, it means a feeling that the danger was over.