What would in your opinion be the best way to hand (London)

I have a Scandinavian client with employees who find it hard to interact with their British partners. Since English is not Scandinavian's mother tongue, they struggle to find out how to handle this phenomena in a best possible way. Their British partners use irony and understatements, sometimes sarcasm and other verbal exercises, which makes them feel rejected or gallantly “put in place”. Trying to overcome the feelings this creates, they would like to learn some tips on the best way to react.

Does anyone have any suggestions about:
1) How it can be handled in an elegant way - by being tactful, tactical and smart - without being rude or offensive?
2) What may be the reason behind - or context - for such behaviour?

I would greatly appreciated your input to this, and I am sure this topic is of interest to others too.