"We thought about this very carefully in the last year and said to ourselves that at the core of our business we are a bank, but we also have a significant technology company embedded within the organisation," he said. "The question that I was asking the management teams [was] do we really want to compete with the cloud providers and people like Google, are we really going to try and do what they do as well as they do it?
"Our conclusion was that it was better for our business if we adopt a cloud-first strategy."
Cloud use cases
The bank began targeting use cases involving very large data sets that require very intense computing capabilities in short bursts, West said.
One is anti-money laundering. West said: "We are running analytics over this huge dataset with great compute capability to identify patterns in the data to bring out what looks like nefarious activity within our customer base.
"The patterns that we identify are then escalated to the agencies and we work with them to track down the bad guys. This is an application that clearly requires massive datasets, great computing capability, but also a machine learning capability to them identify the pattern in this huge data asset."
Another is risk simulations, providing insight into "billions of transactions".
West said: "We need to be able to run complex Monte Carlo simulations on a regular basis to better understand our trading positions and our risks."
HSBC is already using AWS for development and test purposes, and told press that the bank is also working with Microsoft, using its Azure public cloud. It is also using Oracle for software as a service applications.
West said that the bank has been working with "all the big cloud providers" and will continue a "hybrid" strategy, identifying the strengths and weaknesses of each provider.
He said that one of the advantages of Google has been in appealing to its teams of data scientists.
"We spent a good amount of time working with all the different cloud providers and evaluating their products," he said. "If you look at the scarce talent we have around data analysts and data scientists, they need tools that allow them to do their work in a very productive way."
He added: "There is always a challenge to get data scientists to shift from their favourite platforms - they have really enjoyed that experience."
The bank is always working with Google on developing security solutions, he said. The next stage is to begin to move towards using the cloud in production.
"It is early in our relationship, we are still in pilot mode and we hope to get these use cases to production in the coming weeks and months but our experience so far has been very positive," he said.