Good data stories need good data sources. Here are some of the best (click links).
1. Data.gov.uk
Data.gov.uk was launched in 2009 and now has 40,000 non-personal UK government datasets. Organised under helpful section headings including Defense, Health, and Transport, data.gov.uk is as good as a place as anywhere to start. You can filter by publisher, topic and file format. Most useful, however, is the option to organise by date of publication, meaning you can stay one step ahead of the latest data releases.
2. Environment.data.gov.uk
Environment.data.gov.uk publishes official environmental data from the UK government. This includes emissions and pollution data, farming and fisheries. The data can be very dense so it is advised you read the associated literature carefully before starting.

3. Office of National Statistics
The Office of National Statistics (ONS) is the largest independent provider of statistics in the UK. It is also the recognised national statistical institute of the UK. It publishes data on society, business, employment and population. They are responsible for managing the UK census, next due for 2021.
4. Registry of Search Data Repositories
The Registry of Search Data Repositories, or re3data.org, was set up to provide a solution to the problem of “heterogeneous” datasets. In simple terms, its a search tool that allows you to find open datasets collected from academic institutions around the world. If you want to access The Taiwan Fish Database or The World Atlas of Language Structures, re3data.org is an easy way to find research datasets.

5. World Bank
The World Bank collects global data like infant mortality, fertility, vaccination rates and poverty. There’s a lot of data here so the best thing to do is dive in and have a look. The search function is useful for pinning down your exact data.
6. Data.police.uk
Almost all UK police data is in one place at data.police.uk. Download in .csv format or use the inbuilt API function to request data from your console. Knife crime data is held separately by the Office of National Statistics. Also worth checking out is the Stop and Search data at gov.uk.

7. European Data Portal
Europe’s transparency database. Searchable by subject area including Health, Science and Technology and Environment. Many foreign documents are only published in their native language but if you can get past that, this is an excellent resource for cross-national comparison.
8. Companies House
Companies House holds information on all business registered in the UK, including where and in whose name businesses are registered. Download company data in csv or html, although beware some services ask for a fee. You can also set up email notifications to alert you when company details change.

9. Global Open Data Index
The Global Open Data Index collects open-data from around the world. Sadly, not all governments collect information in the same way, so there will be some inconsistencies. If you want to compare data like National Budgets, air and water quality, then this is a good place to start.