The opposite of casual Friday... Fridays are tie days is a tradition for many British regiments, and their retirees. Good excuse to flip the script even if working from home...
The above example is a bow tie worn by Old Fettisians. That is graduates of Fettes (full name Fettes College - which is perhaps confusingly a high school in Edinburgh) - a 'public' school which in the UK means a private fee paying school...
If you are an Ian Fleming/Bond completist you will know that James Bond (and his father Andrew Bond) both attended Fettes. A subtle nod to Bond then above...
The day uniform for Fettes has a completely different and very distinct color scheme; brown and magenta (or "sh* and death" as my attending sister called it - in a reference to John Irving). This connection was applied in full in the teen follow up Bond books - check that blazer;
There is an alternate Fettisian tie that references these wilder colors...