Since both Bentley and Autoglym claim that these products and the wax are recommended for Bentleys I emailed Autoglym and asked about these claims. Here is their reply from customer service (which was very prompt):
Regarding the bespoke range of Bentley products manufactured by Autoglym, we worked alongside Bentley to develop a car care kit that would encompass the products required to maintain the vehicle and attend to any every day soiling or more difficult marks that may occur. We worked with Bentley at every stage of development ensuring that the products and raw materials we selected would be suitable for the wide range of surfaces present on Bentley cars young and old. I’m afraid we do not comment on formulation data for reasons of confidentiality business, although you can take reassurance that by using a Bentley approved range of vehicle care products you are using what the manufacturer themselves endorse.

I guess this might be like Meguires doing the same thing for another auto maker since Meguires makes a wide variety of products. When I first started this quest, I called Meguires, told them about my car type and color and the customer service person recommended the products that he felt would be the best.

 

Regarding the brush included in the Bentley kit - As it turns out, it is not meant to be used to remove the excess wax on the car.

Here is a excess wax removal brush I found on Amazon which is expensive ($19.95 + shipping), but seems to be ideal for the job:

...made here in the USA! Featuring 100% natural premium boars hair fibers, the softest natural brush fiber available, and packing more bristles per square inch than any of our competitors this brush will hold more soap or cleaner and never introduce scratches to delicate finishes.