"We are yet to see any offering in the market that is compelling enough to go down the full cloud path," Girn said. "Service reliability and where data is stored becomes an issue unless you have clear commercial boundaries."

Westpac may be public cloud averse from an infrastructure standpoint, but there are some software-as-a-service applications within the group, which the organization determines through its IT governance process.

"That [software-as-a-service use] is limited and not something around customer information. We make a risk assessment with the business," he said.

The merger between Westpac and St. George has been in progress for two years and ongoing projects are tackling integration -- both internally and with third-party Web services.

When the merger was first announced, the banks put together an IT strategy that looked at needs of all the brands in order to simplify and consolidate where it was deemed appropriate.