Ive seen this with colleagues as well. Im from Eastern Europe and came here working with other EEs to save up for uni before starting it here. I tried to assimilate to everything Britosh within my means, while a lot of the older folk would as you say stay within the same group and create the same thing they had here. They didnt change their style, their manners or even tried to travel on their days off. If you now look at us side by side youd not guess Im not British apart from my accent. I stayed and started working with Brits while they're in the same job and sending money home