Cloud computing might the focus of many enterprises, but Westpac is yet to be convinced of a viable offering outside its own private infrastructure.

Girn said cloud computing can add significant value to businesses in terms of leveraging shared infrastructure, driving down costs and increasing time to market, but its definition remains "somewhat unclear."

"It's difficult to justify the expense yourself [and] from an industry perspective it's about getting clarity on what you mean," he said.

For the past 18 months the bank has developed its own private cloud to allow projects to "rent time" on shared infrastructure for an "end-to-end test environment," he said.

Public clouds, however, are still off limits.