Okay, let’s tackle this. So David Guest has 25 years of experience as a CEO/Founder of a successful software company, which is a significant achievement. However, his education is not specified, which might affect his earning potential. Location is the UK, which is a developed market with a relatively high cost of living. Considering his experience and industry, a rate of $150 per hour seems reasonable, but it's on the lower side. A more accurate estimate would be in the range of $200-$300 per hour, considering the UK's software industry standards.