One car you might like to consider is the Honda FR-V. It has 6 seats. However the newest ones are around 8 years old, so that might exclude it for you. They are however highly thought of in terms of reliability and the 1.8 VTEC engine is excellent if a little short of low down pull.

Not sure if the CR-V has enough of a rear middle seat for 2 child seats plus an adult.

There is also the Fiat Multipla, but (cough) we'll just skip over that swiftly.

Is 15k the budget?

Citroen C4 Grand Picasso with the PureTech petrol engine? Might just get a new one for £15k.

The CRV is almost as big as an S-Max, so if you want something smaller, you'd need to see which of the smaller 7-seaters have Isofix points in the 'very back'. I would hope that most do, as children are the main users of those seats.

Have a look at cars like the Toyota Verso, Ford Grand C-Max, Vauxhall Zafira, Mazda 5 and Citroen Grand Picasso. You're right to prefer petrol: petrol examples will be harder to find but there will be some around. Look at the cars for sale section of this website.

Edited by notagoodname on 08/03/2017 at 16:48

Dependent on the child seat, and the size of the adult, you might find a larger 'ordinary' car will fit the bill too.

With two toddler seats in my Octavia put at the outer edges of the isofix mounts, I can still sit reasonably comfortably in between them in the middle back seat. I wouldn't want to do 300 miles like that, but an hour or so is fine. I suspect you'd find much the same with a Mondeo, Avensis etc.

Just wanted to thank everyone for their advice. We concluded a Toyota Verso was worth checking out and dragged our car seats to the dealership and there is just enough space. And in general we liked the car and so plan to get a 1.8 Verso probably in Excel trim.