The short answer is no.
I'm not a legal expert and this is not intended to be legal advice, it's a summary of items I have found and my feelings on the matter from my understanding of the issues regarding UK law.
You can copy it for your own personal and non-commercial use, but not for others and certainly not to sell it, share it, show a picture of any part of the written pattern on social media or dictate it to others. However, you can post an image of the knitted item, providing you have the rights to the photograph.
However, it all depends if the copyright has been asserted, and if there are any exclusions or not by the owner of the copyright. Now that could be a wool company or an independent knitwear designer.
As a knitwear designer I know just how many hours it takes to write a knitting pattern. That's before the time it takes to knit the item, this time needs to be paid for as well as the cost of the photography.
The work when laid out in a printed book or leaflet or indeed a PDF may look short and not amount to much, but trust me, the maths in a knitting pattern is rather a lot, especially when it's graded for up to 6 sizes!
And it needs to be checked, checked and checked again.
Imagine if your knitting a pattern and all of a sudden the decreases in a shoulder are incorrect, you as the person who bought the pattern and the yarn and needles to go with the pattern would be a little peeved off if the pattern did not work. Reputable pattern writers make sure all works, and the costs for this is reflected in the pattern price.
Copyright is legal protection to an author that gives the owner of the work (in this case the written knitting pattern) exclusive rights to control how or whether a copyright work is copied, either the whole of the work, or a part of it. Images on social media of patterns, of even just a portion of a written knitting pattern are included in this, as is photocopying of a pattern in a shop for example unless the author (the copyright holder) gives permission to do this.
A knitting pattern is a set of instructions. The pattern writer will take great care and a lot of time to make sure these are correct and work for all sizes stated on the pattern. It's always best if there are issues with the pattern to go back to the designer to ask for help rather than to post a picture of the pattern (or part of the pattern) on-line.
Copyright expires after 70 years past the end of the calendar year of the death of the author of the work.
Some knitters like to copy a pattern to jot notes along the pattern as they knit in order to keep a clean copy of the pattern in the book or leaflet the pattern came in, or indeed to print a downloaded pattern they have acquired legally from the internet. This is allowed, as long as it's for personal use and not shared with others.
As the copyright can have exceptions (read the small print on a pattern) most usually come with a licence (permission) to create the work as set out in the pattern, this may for example restrict the sale of the knitted item from the pattern or not allowing multiple knitted copies to be made for sale.
This all comes down to what has been tested in the courts under copyright law as to whether the copyright work is considered 'substantial'.
For example, changing a 1x1 rib on a sweater to a 2x2 rib and knitting the rest of the pattern the same may be seen as substantial, but if you are not sharing or selling the changed pattern and it is for your own use will most probably not be seen as an issue.
Just because the pattern writers name or a © symbol displayed does not mean that copyright has expired or that the pattern is free from copyright.
It's always best to ask the pattern author. Copyright is an automatic right and does not need to be stated under UK and other countries laws that the copyright has been asserted, however for deliberate infringement or commercial sale may lead to criminal prosecution.
This depends if you have a licence from the copyright owner to do so - remember the copyright holder owns the design of the pattern.
No. This would infringe the author of a sale of their work.
Sadly not, the publisher of the magazine will own the copyright or a licence to use it and will have paid the pattern author a licence to publish the pattern.
Sadly not. Some yarn companies give free patterns to encourage yarn sales, but that does not mean there is no copyright or that it can't be infringed.