That pretty well sums up what many people have been saying - these competent persons schemes are really not that much more than a scam and the perpetrators are more interested in their membership fees than in their responsibility to the public good.... my electrician told me that, he can't get involved too much as the governing body is refusing to help (he spoke to his inspector about that matter) as it would mean that they going to have a case against themselves for allowing this kind of people to be certified by them.
IME that's unusual. Different lenders use different criteria - sometimes without actually telling you what they areOne of the conditions of the mortgage being that the rent had to be at least double the mortgage payment.
Mostly I've come across 125% (i.e. the rent must be at least 125% of the mortgage payments), sometimes 145% - but it can vary depending on your other income and the size of the mortgage (LTV).
On one occasion, I went to enquire with a lender, having looked at their offerings online and working out that it could be what I need. So went along to the local branch, gave the details they asked for, and was given a completely different (much lower) maximum loan value. After some discussion, the other person was able to find out (she had to phone someone else) that they used a different figure to what was on their site I commented that this has caused a complete and utter waste of time for both of us, but all they could say was "not enough room on the site for everything"