It's not a chav brand in my opinion,
But you will sometimes see chavs wearing it. Just like you will sometimes see them wearing RL polos/hoodies.
I don't think there are that many chav brands. I don't even think Nike/Adidas are.
It all depends on how you wear it, rather than just what you wear.
I wear Nike Air Max trainers sometimes. Adidas Originals are great too... but there is a time and a place for them.
Oh and just to add - I guess it has something to do with House of Fraser and more internet sites starting to sell the brand, hence it becoming more prevalent. I remember a few years ago, not many my age even knew what TH were about. That's changed now.
I think they market (some of) their products in a similar way to A&F etc. - at least the stuff targeting young people. They have been around for a long time and they cater for a wide variety of people.