Hi Sarah. The criteria isn't set by Walsall Hospital, it is set by your local Primary Care Trust (PCT). Whereabouts do you live, then you will be able to see if anyone else is under the same PCT who can give you some info. I am under NHS North Staffordshire whose criteria is BMI over 50. However, I have had my first appt with Walsall (my BMI varies between 45 and 47) and the surgeon and head doctor both said I would qualify because I have comorbidities, and their guidance said that my PCT funds for BMI over 40 with comorbidities.
First step - find out what PCT you're under.
I would add that BOSPA website isn't that accurate in terms of the criteria it lists for each PCT - it certainly isn't for NHS North Staffs anyway. The best thing is to speak directly to your own PCT (Commissioning Team) unless your GP is au fait with the bariatric surgery criteria.