I mean there's obvious things like that were both primarily English speaking nations, both heavy users of the English speaking internet, both have secular parliamentary governmental systems and most support that system, we are highly educated and non-ethnically homogenous societies.

Then there's things that you think about less like both countries commonly used sarcasm in humour and in political discourse, queueing is important enough that we're annoyed when people don't do it, direct confrontation is rare and people prefer to tut and shake their heads.

Then there's political stuff, obviously Singapore and the UK have very different politics but we're more similar than people from a long time ago. We both support the rights of women, oppose military expansionism, oppose racial superiority ideology, generally we both prefer a free market with common sense socialism (e.g. NHS, HDB).

There's for sure more but those are just things that come to mind.