Q.bougainvillea in pot
My bougainvillea is in a large pot (60 cm diameter by 45 cm high) and have under planted it with 2 thymes, which have grown to full size. Will they restrict the growth/flowering of the bougainvillea? It has a least 10 hours of sunshine daily. I use slow release food and water when the top soil feels dry, usually every other day.

I can't find any research that would say underplanting your Bougainvillea is a detriment to the plant.
Your plant looks wonderful and the Thyme fills in the pot very nicely.
Make sure you water the plant properly and enjoy!