Hi Be*, l think that l might have an answer for you, under employment law, you old employers, are not allowed to give a bad reference, they have two options, either give a good reference or don't give one, and leave it up to your new employer to sort out, l had a similar situation about two years ago, and l needed a solicitor for help, unfortunately l cannot say much about it, due to legal restraints, but, what you could do, is contact the Managing Director of the company, outline, you old position, and also send him a CV, after him to contact the ' second ' employer on the cv, to find out what they thought of you, it could be that, your old employer might have had a gripe, and picked on you, ACAS, could help, if you contacted them, you need to be employed for two years, to have protection, and if you are placed on a trial period, then an employer does not need a reason, to let an employee go, that is the sad part of employment, before, part timers didn't have protection under law, now they do, you can always try
www.gumtree.co.uk (or com) for a job, or jobcentreplus.org.uk l wish you the best matey.