Bearing in mind the name of the forum, here's a bit of info for you.
I wasn't at work yesterday so didn't have a first hand look at it.
However the comment about "brave pilots" does raise a few issues.
First off is that our concerns for our passengers are in three different levels, safety, comfort then covenience (sub divide this into pucntuality then preferred destination). In other words you get to the right destination, on time provided the first two criteria are met. End of. Bravery just doesn't come into it.
We now have two bits of kit that help us do that. Weather radar and windshear prediction. The weather radar is a broad brush approach that shows us where the rain is falling. The display display is colour coded: green, amber, red and magenta. The different colours are calibrated for different size rain drops. Big raindrops need big updrafts to generate them. On a personal basis I find green is no problem, amber is enough to suspend cabin service and have the crew strapped in, red is a no go area by a sensible margin (5 to 20 miles) and don't ever ever contemplate magenta.
Predictive windshear is also radar based and shows areas where the differences in local winds could make the approach unsafe. In extreme circumstances, say the gust front produced by a heavy downpour from a thunderstorm, an aircraft might not be able to to outfly the downdraft and be pushed onto the ground. Has happened and it's not good.
What this means from a practical point of view is that an approach should only be continued if it's safe to do so. Even then I've had to go around from a very low level as gusts have come through and the aircrafty wouldn't have landed in the touch down zone. The crew would have discussed their options prior to making their approach, and would have briefed any conditions requiring them to break off.
Looking at the TAF in the original post, LHR wasn't a cast iron guarantee for clear weather, so for me that would mean an hours holding fuel, plus fuel for a diversion airfield which didn't have the magic term TSRA in the forecast.
Crews don't, as a rule divert lightly. It costs the company shed loads of cash and disrupts the passengers and flying schedule. Also my car is parked at home base. Howver, we don't do brave.
Hope this helps.