Thanks everyone! I feel like maybe I've been unclear and it sounds more impressive than it really is, but I'll take it
That's good progress. 30 miles each way is a big chunk of time out of the day on a bike. Realistically, it's a good two hours riding plus getting changed at each end - adds 5 hours to the day. What's your options for 'poor weather' ?
So just to clarify, as in my OP, it's a mixed-mode car & cycle commute over 30 miles, once a week. I only currently cycle 11 miles each way, so over that distance weather isn't really a problem. But there's always the train if I really don't fancy it. But like I say, I do fancy giving the full 30 miles a go in the summer!
What does it save you in cost each day ?
Return train ticket ~£30. Don't know how accurate those online cost-of-motoring calculators are, but they reckon < £10. So a good saving. (Plus cost of bike consumables, of course; but I'd be cycling for leisure anyway, so I don't really count that)
How are you finding it and what is your daily ride now?
So after a bit of experimentation I've settled on a parking spot that takes ~55mins to drive to, and from which it's an 11 mile / 50 min cycle. To be honest, my comment about the surprising consistency of travel time was in relation to the driving part -- I'm well aware of the general awesomeness of cycle commuting

. But yeah -- even though it's mixed-mode, at rush hour, it's predictably ~1hr drive, ~1hr cycle/showering/etc. So far...