I said I'd give you five hours.
Which is about right, given that in numerous Cardiff - St Albans (smack on that M4, M25, A12 route) trips I haven't achieved less than 3 hours any time this year I think. And St Albans to Ipswich is about 1.5 hours.
Why would you use the A40? It's M4, M25, A12.
Indeed - see above.
As I said, putting the journey into National Rail at the time on Saturday when I posted got a minimum of a 6 hour journey.
Sure, but that is very unusual and due to engineering works on the Cardiff-London stretch o Saturday. The normal week-day schedule is just over 4 hours and that is allowing, to my mind, excessive time to get from Paddington to Liverpool St, which is just a single tube.
You mean it does for you living only five minutes from the station and going somewhere that is only five minutes from a station and setting out at an ungodly hour. And that's fine but it does not alter the point that there are viable alternatives and these might be better for other people in different circumstances.
Sure, driving may be a better option in some circumstance, the train in others - a flight isn't a viable option though.
I note no response to my post about my commute, where there is no viable option for me other than the train.