Be careful to check your delivery very very thoroughly if you get a M&S sofa. I was out when ours were delivered (my sister waited in for the delivery as a favour to me while I was at work) and I didn't really take much notice of them, just sat on them! Then 2 weeks later, I moved them to hoover behind and underneath and found a 2" long deep knife cut in the back of one of them (on the top corner of the back piece). I thought 'oh it's M&S, I'll just ring them and tell them' but they were rude and awful and basically accused me of doing it myself 
.
I contacted Consumer Direct who prepared a letter for me saying that M&S were in the wrong, but they still wouldn't back down. I think what happened was that the delivery men removed the protective packaging from the sofa with a knife and cut the sofa by mistake, then positioned it so that the damage couldn't be seen. They denied this totally and said it was ludicrous etc.
Eventually I sued them and got a new sofa. It took up a lot of time and energy for a whole year of my life. I would never ever ever buy furniture from them again, which is a shame as the quality of the sofas is really good. We've had them for 6 years and there isn't a mark on them (leather). But I wouldn't deal with their crappy customer service again.
Bizarrely, a few weeks after I got my new sofa (and cheque for my court costs, of course) I got a call from someone at M&S head office saying how terrible the whole business was and it should never have happened etc and she wanted to speak to me in detail about it. She made arrangements to call me at a convenient time (when I wasn't at work) in 2 weeks and guess what? Yep, never ever heard from her again!
So proceed with caution. If you have a problem with your furniture that comes to light more than 3 days after delivery, they will tell you to sod off even though legally they cannot do this.