After an introduction to the ESA Herschel Space Observatory including a mission overview, science objectives, results and productivity we examine the process and outcomes of the announcements of observing opportunities (AOs). For Herschel, in common with other ESA observatories, there were no rules, quotas, or guidelines for the allocation of observing time based on the geographical location of the lead proposer’s institute, gender, or seniority (“academic age”); scientific excellence was the most important single factor. We investigate whether and how success rates vary with these (“other”) parameters. Due to the relatively short operational duration of Herschel—compared to XMM-Newton and INTEGRAL—in addition to the pre-launch AO in 2007 there was just two further AOs, in 2010 and 2011. In order to extend the time-frame we compare results with those from the ESA Infrared Space Observatory (ISO) whose time allocation took place approximately 15 years earlier.