Hi bnz, we've been here now for just over a month. I have to say that I am still in shock over the cost of things. We also don't have housing allowance (or school), but were offered additional salary instead. In theory because tax is lower, you make up for higher cost of living. The problem we are finding is that this added salary/tax saving is going to be "spent" 100 times over to cover the cost of high rent, food, flights home, phone calls, etc. etc. So in the end, I think we are going to be worse off.
The biggest shocker is housing. Even coming from pricey central London Singapore rents are extremely expensive. Brace yourself for this. We realised we had to compromise on space, or location, or condition, or price, or something else.
My dd is not school aged, but everyone has warned me about the cost of international schools (and wait lists). Local schools are an option to reduce cost, however the academic culture is very different and priority goes to citizens/PRs. In London we were spoiled for choice in terms of free museums and kids activities. Many things here are paid. I took dd to Gymboree the other day and stupidly spent £20 for a 1 hour session!
Now, to be fair, you can of course live on next to nothing if you are going completely 'local'. But the second you start considering things like wine, or cheese, or tomatoes, or anything that isn't normally found in this region you are in trouble. And if you tend towards the 'organic' choices, you are massively in trouble!
So far, what cheaper seems to be: taxis, eating in food courts/hawker centres (which are usually very good and about £2/meal), any type of manual labour, and live-in domestic help - who (depressingly) you can pay a pittance and only give one day/month off! (Although it seems most expats offer one day/week off).
I probably sound negative, and maybe others will jump in and say my impression is wrong. I'm still adjusting. On the plus side everyone is very friendly, so your social life will probably be very active.
Back to your question: I spoke to a head-hunter, originally from London, and his advice was to calculate it as 1/3 in terms of cost of living and spending power. So for example a salary of: SG$100k in Singapore (for an expat) is equivalent to £33k in the UK.
I hope this helps! Excuse the essay!!!