Great Western Coffee Shop

On Bank Holiday Monday I went to Wells with some friends. We took the 376 bus from Bristol bus station, getting off near the radio mast on top of Penn Hill and walking a few miles through some beautiful bluebell woods. In the cathedral we were handed leaflets which included directions to Wells by various means of transport. Under train, it said the nearest station is Castle Cary, about 13 miles away, and "taxis are available at the station". Obviously it depends how far you've come, what you're doing, how much time you've got and in various ways who you are, but 13 miles by taxi seems to me to be stretching the limits of what is a train journey. I don't think it gave any information about buses from Castle Cary (Google says this is possible using the 667 then changing to the 376, taking about 90 minutes).

Beyond the specific case of Wells, how long a planned taxi ride would you consider compatible with a journey that's mostly by train?

Probably more than I would like with the decline in (disappearance of) funding for "rural" bus services.

True, though I guess the 376, which runs from Bristol to Street, still has funding. At any rate, a return to Wells costs £7, which struck me as good value for the 22 mile journey compared to £13 (I think) for a return from Bristol to the airport, which is only about 8 miles.

Only £6 when bought on the m-ticket app, the metrobus i-points or in advance on the TravelWest smartcard.

I tend to think of a journey as being primarily by train if the train fare is significantly more than the taxi fare.

Example, London to Minehead. Train fare to Taunton £170. Taxi fare Taunton to Minehead £60. A train journey IMHO

Example, Berrylands to Sutton. Train fare Berrylands to Surbiton £3. Taxi fare Surbiton to Sutton £40. A taxi journey IMHO.
The only reason for taking the train to Surbiton was a lack of reliable taxis in Berrylands It was quicker and simpler to take the train to Surbiton at which place there is a taxi rank.

I'm surprised at these journey choices, given you profess elsewhere to using the most environmentally friendly option elsewhere (regardless of any compromise on speed of journey).   

The bus to Minehead would undoubtedly have a lower carbon footprint than a taxi, though might take a smidge longer.  You can even buy a through ticket and as an example, the 1303 from Paddington has a 10 minute connection at Taunton and then a 1hr 15 bus journey.  Integrated transport indeed!

And the rail journey from Berrylands to Sutton takes just 40 minutes (probably as fast as your choice) and costs £3.90, (just 90p more than the fare to Surbiton!) though admittedly neither train probably has a buffet, let alone a restaurant car, so I'm guessing that rules it out as an option?

The journey to Sutton was many years ago and was a one-off to visit a dying relative, cost and carbon emissions were secondary to getting there quickly. Public transport throughout was not an option as I knew not how to get from the station to the nursing home.

The bus from Taunton to Minehead is indeed much lower carbon and also a lot cheaper than a taxi. I use the bus where possible. ALL my recent journeys have been by bus.
However when I was working/living in London but visiting my Mother in Minehead, I often had to get a taxi as the last bus departed Taunton before the arrival of the train from London.

Odd name, Berrylands. I know where it is because I once rode my bike through there so late on a Saturday night that some people would have considered it Sunday morning, having left Wimbledon or thereabouts that morning (if you don't understand why I did this, no explanation would help; if you do understand, it's already too late for you to be saved). I'd taken the train up to Clapham Junction on Friday and back on Sunday; but – the relevance, just about, is – I saw that as three journeys; up to Clapham Jnctn, ride, back from Clapham Jnctn. But then it was three separate days, just about. No taxis though.

National Rail gives a fare of £52.60 London Paddington to Minehead (including bus fare), can't see any fare at £170 apart from a 1st class anytime single @ £174.80?

The fares that I quoted were only approximate, from memory, and yes it was a first class anytime single.
Cattle class no good as wanted to book in the Pullman.
Advance first class offered only a modest discount and is non refundable if some work related c0ck up stopped me getting the train.

Could actually do it for £1.50 by walking over to the X26 bus.