I view things in a slightly different way.
Firstly, always be courteous and polite. Besides, it makes good commercial sense. Yes, change shoes at the door and ask if it's acceptable to answer the phone etc. I will usually say something like, "would you excuse me while I just divert this call" I wont actually speak to someone on the phone if I'm in conversation with a customer.
Now, us Brits are a soft touch, and I'll illustrate it with this scenario,

Imagine a businessman visiting Japan. He would be expected to initially greet his host with a bow. Reverse the situation with the Japanese visiting here. We're still expected to initially greet our (now) guest with a bow!
Generalising, we are an open, giving and caring society who open our arms, and doors, to one and all. And we bend over backwards to accomadate one and all. In my view, if people want to come here and do business with us, or live in our society, they should be prepared to embrace what we have to offer. Not change or set up a little "just like home" community.
Having said all that, you get Brits emigrating to, for example, Spain, and they want to live in a community with an English pub, have egg and bacon for breakfast, a chip shop on the corner, maybe a little C of E Church (just for weddings and funerals) and swear at the locals who are driving on the "wrong" side of the road.
I suppose there are no winners and we're creatures of habit looking for "just like home" comfort :

Safe and happy cleaning

The Ken