Hi Wayne
I recently arranged a mortgage with HSBC and can pretty much agree with what Cindy has said. HSBC don't use the multiplier when you go into the branch. They added together insurance, council tax, water rates, proposed mortgage payments, loans and credit cards then worked out this as a percentage of my monthly income. As long as it is below 60% they will usually lend. Of course they are all too happy to add in mortgage repayment protectors and income protectors but it's up to you if you want these.
Hope this helps,
Brian