Billionaire Denis O’Brien’s ever expanding field of business interests both here and abroad has always reflected his appetite to take a gamble on a new venture or a traditional industry that needs shaking up.

Just now he is the focus of attention in Dublin’s commercial property market where he is making the running in a campaign to have new office rents in the south inner city bumped up from €35 to €45 per sq ft.

O’Brien is pinning his hopes – and his money – on the site of the former Canada House office block at the junction of St Stephen’s Green and Earlsfort Terrace.

The old building is being demolished to make way for a top-spec €25 million office block with an overall floor area of 6,880sq m (74,000 sq ft).

It’s the first major speculative office development in the city for more than five years and the consensus is that if he hits his target then the banks might start funding other developments in the city.

Otherwise the top rents will stay between €30 and €35 per sq ft – too low still to persuade the banks to open up their purse strings.