In March 2021, the BBC Shared Data Unit reported on the problems faced by 300,000 children of UK prisoners and concerns that they had been "forgotten" during the pandemic.

These included delays to a "military grade security" video call system which was not fully rolled out until nine months after the start of the pandemic and had suffered a range of problems, and variations in when prisons allowed in-person visits after national and localised lockdown restrictions.

The BBC has found that, while more than half of prisons resumed visits by the end of July, some 5,000 inmates had to wait until September or later.

The Ministry of Justice said: "There is no question our response has saved lives and helped protect the NHS, with infections and deaths in prisons significantly lower than predicted at the start of the pandemic." It said it was also working to improve the video calls system.

• Prison populations, category, and lockdown dates
• Methodology and briefing pack
• Report: Children of Prisoners: Fixing a broken system

• Spokesman, Ministry of Justice (MoJ)
• Jodie Beck, co-founder, prisoner family support network Our Empty Chair
• Jake Richards, barrister representing seven families in a legal action against the Ministry of Justice
• Sarah Burrows, chief executive, Children Heard and Seen, which provides support to families with a parent in prison
• Michelle, from Lincolnshire, who has been looking after her and her husband's three children alone since he was imprisoned in late 2019
• 'Jessica' (not her real name), who has four children and whose husband is in prison
• Statement, Inquest

• Histogram: Coronavirus daily cases, Feb 2020-Mar 2021
• Infographic: Lockdown rules for England from 29 March

• Scraper (Python notebook) of changelogs on gov.uk webpages for each prison
• R notebook: Using the Wayback Machine API to find snapshots of prison pages

The Shared Data Unit makes data journalism available to the wider news industry as part of the BBC Local News Partnership.

The story was used on BBC local radio stations in Kent, Shorpshire, Teeside, Leicester, Bradford and Berkshire. It also featured as television packages on BBC Look North, BBC South West and ITV Central.

Stories written by partners based on this research included:

• Your Thurrock: Prisoners allowed visits for just 100 days in 2020 31 March 2021
• Sunderland Echo: North East prisoners had no visits for most of last year after pandemic rules 30 March 2021
• Yorkshire Evening Post: Covid prison lockdowns: Family visits ban at HMP Leeds and other jails leaves children 'hardest hit' 30 March 2021
• Saffron Waldon Reporter: Prison visits were limited to 100 days in 2020 5 April 2021
• Dunmow Broadcast: Prison visits were limited ti 100 days in 2020 5 April 2021
• Belfast Live: Families and children 'hardest hit' as prison visits in Northern Ireland were limited to 93 days in 2020 9 April 2021

You can find all coronavirus-related stories by the BBC data units tagged 'coronavirus' here