Maybe a little controversial, perhaps heresy, and possibly risky, but...Simpsons are no longer for me. Why?
I have used 'The Duke' for several years, but not for as long as I've had many other brushes, including every type of badger, several synthetic and custom Cadman brushes (here I get on my knees and bow). I have always looked after my brushes in exactly the same way... rinsed well after use, ensured they were as dry as possible and then aired in a brush stand to ensure no build up of scum at the knot. I have also used them in similar routines: same soaps, creams, water temperature etc; never too hot and never too much squeezing to damage the bristles or the knot glue. I have also rotated their use to ensure no brush ever stood unused or uncared for. BUT...
Of all my brushes, the only one which started to repeatedly shed hair was the Simpson's Duke (a genuine one purchased from a reputable shop). After a while, and after trying various 'cures' from recommended internet sites, I decided it was getting so bad that I just wasn't enjoying shaving with it any more. And yes, I did check multiple forums and found lots of threads where people had similar problems with their Simpsons brush shedding hairs, and most of the feedback seemed to be quite similar: Maybe you were just unlucky as they're usually very good but if you send it back Simpsons have really good customer care and they will replace it...etc...etc. Well, I have no doubt that they would replace it with no qualms, BUT I don't want to go to the trouble of sending it back, and I shouldn't have to because I have never had to do that with any brush before, many that I still have and have never ever shed a single hair. And anyway, how come it was so easy to find people asking about Simpsons brushes shedding hair?
I'm sure I'll get a lot of flack for this but my general perception is that Simpsons brand is now so embedded in peoples' minds that they might ( I say might) just feel they can get away with a few more quality issues than others. For me, the true quality of a brush isn't that the supplier will replace it quickly but that it is less likely to need replacing in the first place. I repeat: none of my other brushes had this problem and most were cheaper by far (other than the Cadman's...but hey, they are Cadmans) and I honestly don't want to spend on another Simpsons brush and risk disappointment. 'The Duke' I had was excellent for quite a while and you will find my praise heaped on it elsewhere in this forum, but for a brush that many say should last a lifetime...well it didn't. So Simpson's brushes for me...meh.
(Apologies to the many Simpsons brush fans out there; this is of course my own narrow-minded opinion and not intended to be a slur on Simpsons...perhaps a company that sells so many brushes with such a focus on quality is more likely to be held to a higher standard.)