Beware - the Rishworth website states that pilots are "employed by our UK crewing company" - an employment agency leasing pilots to other airlines, specifically, Norwegian. However, there is no reference to this so-called "UK crewing company" in the Contact Us section of the Rishworth website. I suspect it is a broom cupboard somewhere in Crawley.
All employment agencies in the UK are regulated by:- The Conduct of Employment Agencies and Business Regulations 2003. Any pilot engaging with Rishworth via their "UK crewing company" should be familiar with this legislation.
So it seems that the contend of the bond is unenforceable for the following reasons:-
In the UK registered unemployed are obliged to seek work or have their benefits reduced and in some cases stopped entirely (JSA - Job Seekers Allowance regulations). Therefore, if you are registered unemployed (even for a week), interview for a position with Norwegian and offered employment, you are obliged to accept employment at the first opportunity or have your benefits stopped. Effectively, you are forced to sign a bond against your will. If at some later stage you decide that the working conditions are not to your liking (much has been written about the shameful management etc.), and seek alternatively employment, you are prevented form doing so by virtue of the bond. This is effectively Indentured Servitude and illegal under the UK Human Rights Act 1998 and European Convention on Human Rights.