In life, as well as in business, it’s best to avoid threats unless you’re prepared to see them through.

So former BHS owner Sir Philip Green will, after all, turn up at Westminster today at the appointed hour of 9.15am to face MPs. That's one-nil to the politicians before the session even starts.

By threatening not to attend the hearing into the collapse of the department store chain, Green had backed himself into a corner. His attempt to railroad the committee into the removal of chairman Frank Field was always bound to fail, and has served only to further incense the politicians.

Field, chairman of the work and pensions committee, had incurred the retailer’s wrath by publicly declaring that MPs “will just laugh” at the retail tycoon if he were to offer anything less than £600 million (€755 million) to plug BHS’s pension fund shortfall.

Green responded with a furious threat to boycott the hearing, accusing the veteran Labour MP of conducting a “trial by media” and attempting to “destroy my reputation”.

Quite what is left of Green’s reputation should be apparent by the end of what was already certain to be an acrimonious session today, as anger mounts over his role in the collapse of BHS and the plight of its 11,000 employees and thousands more pensioners.

Dis

credited Green sold the business for a token £1 just over a year ago to a consortium led by the now widely-discredited Dominic Chappell, a three-times bankrupt former racing driver with minimal retail experience.

That sale process is now under the microscope, as is the £571 million deficit in the BHS pension fund. Fifteen years earlier, when Green bought the business for £200 million, the fund was in surplus.

Green has already been branded the “unacceptable face of capitalism” by MPs and there are growing calls for the retailer to be stripped of his knighthood.

Ahead of today’s session it would probably have been wiser for Field to have restrained his rhetoric, but, as incensed as Green was about Field’s inflammatory comments, he should have known better than to threaten parliament.

So the billionaire was forced into his inevitable climbdown last night. “Having given long and hard thought to the matter, I have decided I will attend tomorrow morning, hoping and trusting that the committee will give me a fair hearing.”

He added: “This will be the first and only opportunity I have had to tell my side of the very sad BHS story and I will do my best to answer all the questions put to me in an honest and open way.”

Mike Ashley

The investigation is a joint one between the work and pensions committee, which Field chairs, and the business, innovation and skills committee, whose chairman,

Ian Wright

, led the questioning at last week’s gripping session with another controversial retail boss, Sports Direct’s Mike Ashley.

Ashley, under fire over working practices at Britain’s biggest sporting goods retailer, mostly managed to keep his cool under close questioning from MPs. But will his notoriously combustible fellow billionaire manage to be similarly stoical under an onslaught of hostile questioning?

There’s been no shortage of advice for MPs on how they should approach Green’s inquisition, with most publications compiling their own lists of suggested questions. (The profusion of helpful suggestions may in part be due to the fact that that, at the explosive hearing into BHS last week, MPs failed to ask Chappell if he had, as was claimed, made death threats against his former chief executive).

For Green, one of the key questions today will be why on earth he chose to sell BHS to someone with as little retail experience, and with such a dubious financial background, as Chappell, and why he provided financial support to him during the sale process.

Little investment

He will be questioned about why there was so little investment in the business under his ownership, a factor that certainly contributed to the collapse of the 88-year-old department stores chain.

MPs will want to know how its pension fund managed to go from a surplus to such a substantial deficit and why the scheme was not restructured once the scale of the deficit became apparent.

But the most important question will be how much of Green’s own fortune he now intends to put into the pension fund. Field may have said MPs will laugh if the figure is less than £600 million. But, whatever Green’s answer, don’t expect much mirth at Westminster today. Fiona Walsh is business editor of theguardian.com