B&W vs Sony: Which are the noise-cancelling kings?

We pitched the B&W PX headphones against Sony's WH-1000XM2 to crown the ultimate champion

Wireless headphones are now firmly in the mainstream, but to really treat your ears you'll want to go down the noise-cancelling route too.

The good news is that there are two new premium options available in the form of the Bowers & Wilkins PX and the Sony WH-1000XM2. The bad news is that choosing between them is nigh-on impossible. 

We'd rate both above the Bose QuietComfort 35s, themselves a superb pair of wireless noise-cancelling headphones, but which pair do we ultimately think is best? We put the pair head-to-head to find out which deserves a place in your travel bag.