Equestrian Online Ursula sells a range of secondhand (and new) saddles. Located in Southbridge.
When it's not the saddle - it could be the girth... A big shoulder or a girth groove at/in front of the saddle, can make a saddle that fits well, move up on to the back of the shoulder. Causing the horse to lose movement. These shaped girths can help with the misalignment.
Dr. Deb Bennett Ph.D Horses from the viewpoint of paleontologist and horsewoman. Jane Savoie American dressage rider and trainer. Great website to help with training at home. When regular lessons are beyond the budget, or if you find it hard to access a suitable trainer in your area. Also worth searching YouTube for her short, easy to remember, videos to watch before your next ride.
Jenny Paterson Calm Healthy Horses. Having trouble with your equine friend? Could it be in his diet?
Local Saddleries... Saddlery Barn Local saddlery and stockists of Bates and Wintec saddles, and Ogilvy saddle pads.
Information on straightness: Marijke De Yong Free e-book on Introduction to Straightness Training.
Saddle Pads with pockets for 'shims': Uberhorse Supply the stunning Mattes Correction Pads. True quality sheepskin half pads, saddle blankets with pockets for shims/inserts to tailor saddle fit. Available in any colour combination - limited only by the limit on your credit card!!
Carousel Equestrian Suppling high quality Lambskin products that wont break the bank - Half Pads or saddle blankets with pockets (to adjust the fit of your saddle).