In a small pot or bowl, combine the chicken seasoning, then use it to coat both sides of the thighs.
Place a large pan over medium-high heat and add 1 tbsp oil. Once hot, add the thighs and cook for around 4-6 minutes on each side, or until lightly charred and cooked through the centre (timings will depend on the thickness of the thighs - safe internal temp for chicken is 165F/74C if you have a thermometer).
Remove the thighs from the pan and place to one side, then lower the pan heat to medium. Melt in the butter, using your wooden spoon to scrape any flavour from the base of the pan. Stir in the flour to create a roux, then gradually add the stock, whisking as you go to prevent lumps from forming. Stir in the Worcestershire sauce, then bring to a gentle simmer for a couple of minutes until it thickens.
Meanwhile, use two forks to roughly shred the chicken thighs. Add to the gravy (alongside any resting juices), then stir to combine. Simmer for a minute or so, just to marry everything together. If the gravy is still a little thin, just continue to gently stir/simmer to thicken it. If it over-thickens, just stir in a splash of stock (or even water if you've run out of stock).
Check for seasoning and adjust if needed, then serve and enjoy!