M&S e-gift voucher question

[HotelCaliforniaOnRepeat]

Can anyone tell me if I have to print the vouchers out for store use? I know they don't keep them when you use printed ones as you have balance left, but I'm hoping they can scan it from my phone?
I've tried tweeting them to ask before I go. I don't have a printer at home so need to go out to get them printed first if necessary.
Very grateful for any advice.

It says on the voucher that you have to print, but you don’t!

Yes they can definitely scan from your phone, I've done it loads of times.

They just scan mine. I get them regularly and they just scan your phone, or you can do it yourself and the self serve too.

Ah brilliant! Thank you so much for replying.
Makes my life much easier!