Can I use a non barcoded stamp with a barcoded one?

[wondabar]

I am sending a letter to France and cannot believe it is £2.20. I have a £1.70 stamp without a barcode and have added a barcoded Second Class stamp to bring it up to over the correct amount of postage. Will I be able to send this? I have Googled it and there seems to be conflicting advice.

Yes the non barcoded stamps are valid until july this year

Thanks so much. That is very useful.