We have had the offices done new furniture etc, but just got cheap leather chairs, 2 of us are finding after being sat down a while getting bad backs, can anyone put a recommendation forward for a chair with back support

Or a chair without back support?

I have one of these at home and find it immensely comfortable for long periods – it's a Stokke (Varier) Balans chair.

The Hermann Miller Aeron chair is probably the best for ergonomics, I know a couple of guys who use them to either help their bad backs, or to prevent them. Incredibly expensive though (£900), but worth it apparently.

Humanscale are also apparently good, and not quite as eye wateringly expensive as the Aeron chairs.

Can't say which chair as we don't know your particular issues. Don't your employers have a legal requirement to perform a workplace risk assessment including the aspects of using the desk / computer etc? H&S can be your friend.

Don't mess about get yourself this beauty by the late great charles eames and just sit back and watch others work, doubt your boss will agree.

Just picked one up in Ikea for £110

Can't remember the name but it has a tall back with a head rest and is very comfy. Office work approved and 10 year guarantee

A Herman Miller Aeron if your feeling rich, swiss ball if your feeling poor.

As Nick1c suggests above, try a Swiss / gym ball of the right size combined with the right height desk. I use one and swap between it and a posture chair like the one at the top. But then I work from home, and don't have workmates to take the p!ss.

Seriously though, sitting on a gym ball will help. But see a Chiropracter or Osteopath first and see what they suggest, too.

I'm currently sitting in a KH1 Symphony:

(pic from http://www.seatstore.co.uk)

Which I bought myself after back problems while working from home.
I can adjust seat height, tilt & depth, back height & tilt, headrest height and tilt, armrest width and height.
It's set up perfectly for me and no one else is allowed to adjust it.

It was ~£200 from an office furniture place in Newcastle. Sounds like a lot, but I use it for 8 hours a day and it's a complete bargain compared to the Ergohuman or Hermann Miller chairs which will cost between two and five times that!

See also:
Investing in a Quality Programming Chair (CodingHorror.com, July 2008)

No question in my experience – http://www.waveseat.com/

Looks like some hippy hebden bridge nonsense, but is amazing. Literally changed my life when I had a really bad back.

I bought a Herman Miller Aeron for use at home when I started predominantly working from home. Helped my back no end and stops me slumping in front of the PC.

Try fleabay, less than half price for s/h office clearance chairs. The one i got looked brand new.

I've got one of those Balans chairs at home, does nothing for me apart from making me slouch more and my back ache, but ymmmv.
I've found a mckenzie roll on the back of a normal office chair works well for me.