Given that, to quote Mrs Elphicke, Mr Johnson has announced "that the law will be changed to ensure workers are paid at least the minimum wage" and that consequently P&O's "mass sackings are not only bad business behaviour – they are self-defeating", I'd hate to be the civil servant tasked with drafting the legislation. Presumably the (UK) minimum wage will apply to all maritime(?) routes of a certain type and/or from certain foreign ports that enter the UK, rather than simply to operators registered here, or vessels flagged here.
It'll be interesting to see how P&O responds, given their "if we don't halve the wage bill, we'll go bust" stance. I note that the FT reports that the Canterbury, Norbay and European Highlander are effectively mortgaged to The Merchant Navy Ratings Pension Fund to secure P&O's debt to it of £146m. Employer debts to a (DB) pension fund are not unusual, but making no "voluntary contributions" since 2006
and for the fund's trustees to appeal to The Pension Regulator and the government for help in obtaining the monies, is. See
https://www.professionalpensions.com/news/4046987/mnrpf-calls-government-tpr-intervene-gbp146m-deficit-share. Were P&O to go under, one wouldn't want to see three ships go sailing out.