@ Woody Assuming the short wall next to the "W" is the front of the house (as it is on the OP's drawing) then your method of measurement is identical to mine, though your angle is more obtuse.
So what are we arguing about?
It's the widest point as measured along any line parallel to the frontage. Or to put it simply, it's the smallest gap the house would fit through, keeping it in exactly the same alignment, not twisting it.
Obviously it's not ANY direction, because that would clearly be the front left to back right corner, which would be stupid.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local