I regularly operate on the China to Heathrow route and in winter the fuel temp always goes to around -42c sometimes -49c after around 6 hrs of flight.The minimum temp the fuel can drop to is -40c if USA fuel used and -49c for other countries. The engines can be at flight idle for around 20 mins during the descent with temps a lot lower than the fuel would have been on short finals which would have been around -8c or even warmer.
I'm pretty sure if there was any ice present it would have accumalated long before then and most certainly flagged up in the descent.