Don't know about Jet2, but Line Maint Engineers in many companys wear pilot style shirts / ties, and many even use robust flight cases to carry doc's/ laptops, AMM's etc. ( sometimes even festooned with stickers of the LME's favourite type!)
In some cases they even wear epaulettes, generally with a purple stripe between the gold bars. ( Historically associated with Engineering )
Could you perhaps have eyed two such gents passing through security?
In case you are interested, many will suggest on PPruNe that the purple stripes came about as a result of regal recognition of the bravery of Titanics engineers (who stayed aboard) - but the colour purple was used to signify engineering long before she had ever set sail.
In early military days before modern insignia, colours were used to signify different branches - and the Corps of Engineers wore purple..
