I'm surprised that no one has answered you as yet.
But possibly as you have asked for quality and form as being major factors it's hard to recommend something for £50.
It's also down to personal taste!
Do you want a folder? If so - a locking or non-locking blade? Want do you visualise using it for? Preparing game or a picnic? Cutting wood?
There's so much choice out there it may help if you can be more specific, then I am sure you will get some recommendations.
Welcome to BCUK!