Posting restricted items

[fairgame84]

Sold a spare charger and 2 spare batteries for a digital camera for 99p +p&p.
Went to post them via RM and the post office said that they do not allow lithium batteries to be posted if they are not inside the device.
I don't have the digital camera because it broke beyond repair so I binned it.
I messaged the buyer to let them know that I couldn't post the item and cancelled the sale.
The buyer has messaged me to ask me to post them anyway and just not declare that they are batteries. He said that 2 other sellers have done this and that he needs the item for a school camera club.
WWYD?
I feel bad that I've had to cancel the sale but I don't want to break any laws.

most people would break the rules.
Would another courier, like MyHermes, take them? Worth asking.

I'd send them.

I would send them too, obviously don't tell them they're batteries when the post office person asks what's on the parcel

I've sent them. I went to a different PO and they didn't ask what was inside so I didn't have to lie.

I was warned at the Post Office that the parcel would be scanned and they would know it was a battery. The parcel would then be disposed of.

You can send batteries if they are in a plastic storage container. You also need to fill out a form which you will find on the Royal Mail website and stick it on your parcel.

The problem is that if they are not isolated (ie in the camera or device or in a storage container) in certain circumstances they can short circuit and cause a fire or explosion/skin burns. Bear in mind that if you have them stored in your home without protection there is a slight risk. If you haven't got a case you can buy one for a couple of quid on ebay.