Confused - put on postage or not for UK election vote?

I seem to have a mixed message as to whether or not I need to put a stamp on my voting paper to send back to UK. On the front of envelope it would appear that I don’t need to put a stamp but in the instructions it says postage ‘will be paid if posting in the UK’. Anyone know? I don’t want to miss the chance to vote by it going missing.

IIRC, the same issues were raised at the time of the in/out referendum.

The consensus at the time was was that the postage would be paid in the UK (as indicated on the return envelope) and adding french postage stamps would add to any confusion.

It was also mentioned at the time that confusions arose at french poste offices; when asked, some offices said that post had to be applied but when this was checked with official sources, it was confirmed as nonsense and that the international licence sticker on the envelope was sufficient to ensure safe passage to it’s destination.