Marks & Spencer has had some well publicised problems over the years, but the good times have returned recently. But changes are still required to spur the business on and while group finance director Ian Dyson might not have the profile of M& S chief executive Stuart Rose, over the next five years he will hold an integral role in this change.

M&S is totally revamping its stores, supply chain, IT, finance, and everything else in between. On top of that, and integral to all it changes, is Plan A. M&S has given itself until 2012 to be carbon neutral across UK and Ireland, while also sourcing new eco-friendly partners and trading in a fairer 'fashion', a scheme that will cost £200m. 'There's no Plan B', goes the marketing spiel.

For Dyson, who also holds responsibility for IT and property as well, he expects to be kept very busy. 'We're dealing with Plan A, finance, IT, property, adding 20% extra floor space, new store designs moving the business to the next stage of growth gives us a tremendous amount to do. I'm hardly likely to get bored.'

Integrating corporate social responsibility in the finance department might seem tricky, but Dyson already has examples of finance's input into the topic.

Dyson led the company in its search for backers of a £400m bond. Plan A was at the forefront of M&S' strategy.

'We did a beauty parade of which bank to use, and their green credentials were a key part of it. Morgan Stanley and Citigroup said it was the first time they'd been asked about that, but to be fair both produced info about what they do.'

There are pragmatic business reasons at play. Dyson says the company believes it will set itself apart from competitors, 'but at the heart of it is a desire to make a difference'.

Dyson may be finding success in business now, but warns others not to jump out of practice too early. He says his biggest regret was leaving Arthur Andersen after gaining his qualification, a mistake he rectified by returning to the fold'. "I'm qualified so there must be something better than this" was how I thought, but leaving made me realise what a good organisation it was, how much I had learnt... returning was the best thing I did.'

He spent another seven years at the firm, beginning in audit, then four years in consulting hospitality and leisure, with a combination of audit and consultancy clients.

For Dyson his current role is the type 'you call up your mum to tell', and it takes a certain type of person to rise to the top.

'There are hundreds of qualified accountants who are bright, but attitude sets people apart, the ability to take on responsibility, to make things happen and not be frightened,' says Dyson.

'Secondly people management is critical in any aspect of business... getting good people around you is critical who you know will deliver. Never be frightened or threatened of getting good people around you who will push you harder.'