Since 2016, the UK Government has been running an open-source, cross-government Platform-as-a-Service (PaaS) to make it easier and cheaper to build government services. The GOV.UK PaaS is built on BOSH and Cloud Foundry, and is deployed using Concourse. Concourse is "an open-source continuous thing-doer", with abstractions that help build pipelines quickly, and for extending the behaviour of the system. This presentation will provide an introduction to Concourse, and then describe how the GOV.UK PaaS team use Concourse to continuously deploy a whole PaaS whilst ensuring high-availability and minimal impact to services and users. Toby Lorne is a site reliability engineer working at the UK Government Digital Service on the GOV.UK Platform-as-a-Service. This presentation is split into four parts: An overview of the architecture and implementation of GOV.UK PaaS: Terraform - a tool for managing infrastructure as code; BOSH - a tool for release engineering and software lifecycle management; Cloud Foundry - a set of components for Platform-as-a-Service; Prometheus & Grafana - monitoring and visualisation tools An introduction to Concourse: how it works; the abstractions; the design decisions, patterns, and anti-patterns A walkthrough of the pipelines used in deployment and development An examination of patterns used in the GOV.UK PaaS deployment pipeline, and how you could use these patterns in your pipelines.