Hey TS I don't have the answer to your question, but just wanted to add - consider the potential benefit (non-tangible) of:

1.Additional international working experience
2.Potential to come back to Malaysia after about 5 years under the returning expert program (no income tax for 5 years etc.)

All the best and do share your final decision !

Thanks for the feedback. I understand your point about salary should be about merit and not living cost, its a valid point.. I've mentioned that to my friend too, off record.

Im putting professional ethics aside for now so I don't care if he sees this from either a friend's or a manager's perspective.
Plus, this isn't just switching companies but countries too, with a family. I want to show them, that coming to the UK isn't in fact an upgrade....for me at least.

What I've stated is the cost of necessities, not lifestyle. So where do I spend less? Downgrade and live in a studio? Even that doesn't help.
From that spreadsheet I learn that there is little to no chance I can get a salary that can provide me with a better standard of living than what I currently have in MY.
They have to pay at least £6k per month to make this work, and from what I gathered, that is the manager-level salary (just a level above me) in that company.
So what are the options then, either the company absorbs some cost or they let me work from Malaysia.

It's a long shot but if none of it works, so be it. They can continue their search and I can go around walking and rocking like a peacock, bragging that this big-name company wanted me, but I said "Thanks but No Thanks"