Google routed me to Paddington (via Bakerloo) and then the Heathrow Express. I was probably lucky with departure times when I searched though.
(Heathrow Express is expensive compared to the Underground though, but if you were making this sort of map you'd probably use it as it's the faster service).
(Heathrow Express is expensive compared to the Underground though, but if you were making this sort of map you'd probably use it as it's the faster service).