I find experiences such as this incredibly annoying as you obviously have a wealth of experience and a very positive attitude.
It is true that employers can currently pick and choose and are sticking to candidates in the same sector because they have a wide choice. Of course, this situation won’t last forever but doesn’t help you just now. Have you really scrutinised your CV to ensure that you are selling all of your skills? Are you emphasising your entrepreneurial and commercial abilities and making the link between them and the post for which you are applying in your cover letter?
One thing that did occur to me is that you would be ideally suited to mentor and support other people who want to set up in business. It may be worth sending speculative applications to organisations such as Business Gateway or look at the Direct Gov site as it offers a programme to unemployed people where they are allocated a mentor to set up in business. Both organisations will obviously need staff to coach and support individuals.
The other person who posted is right in that there are some sectors where entry level posts are available, particularly in the care sector. The organisations who provide these types of jobs are actually more interested in your values than what you have done previously.