Penny Mordaunt says Boris Johnson's Covid WhatsApp messages went missing

Government minister Penny Mordaunt is the latest witness in the government's Covid inquiry to have an issue with missing WhatsApp messages.

The leader of the House of Commons said that two years of WhatsApp chats with Boris Johnson had disappeared.

Mr Johnson previously told the inquiry that he had lost about 5,000 messages.

His spokesperson told the BBC that he has "sent all relevant messages in his possession to the inquiry and has complied exactly with their requests".

Ms Mordaunt, who was paymaster general at the time, wrote in her witness statement: "I could find no WhatsApp messages between me and the PM between 20 March 2018 and 22 March 2020."

She asked 14 times for a meeting with Boris Johnson's chief of staff regarding the missing messages, "but had no response from his team".

Later on, she was told that she would have to pay tens of thousands of pounds in order to have her phone forensically examined, because the device belonged to her and not the government.

She added that she had since discovered that a similar problem has occurred with WhatsApp messages exchanged with Michael Gove, who was chancellor of the Duchy of Lancaster at the time.

So can WhatsApp messages simply vanish?

Chats are stored separately on each person's device.

So if Person A and Person B are exchanging messages, then both of their phones will have a full, and separate, record of their conversation.

Messages can only be deleted for everybody up to 48 hours after they are sent - and a note appears for all participants saying this has happened.

But any messages older than that can only be deleted by someone on their own phone.

So if Person A deletes a message that is more than two days old, Person B will still have it.

It can only be deleted from Person B's phone by someone who physically picks up that phone and gets into their WhatsApp account.

There's also a feature called disappearing messages.

But that feature only launched in the UK in November 2020 and messages sent before this was switched on would not vanish.

Boris Johnson said that he factory reset his phone. This would not affect the record of his conversation with Penny Mordaunt that was stored on her phone, even if he no longer had it.

He also said he changed his number. Again - whether he started a new WhatsApp account or transferred his old one to the new number, this would not affect the data stored on Ms Mordaunt's phone.

Finally, he mentioned a WhatsApp server outage at the time. An outage at WhatsApp HQ might prevent message sending, but it would not affect the content of messages already sent.

WhatsApp messages are never stored on WhatsApp servers.

If they are backed up, they will be stored on either Apple or Google servers, depending on whether the phone is iPhone or Android.

And they are stored using end-to-end encryption, meaning that only the sender and recipient's devices can read them.

Even if WhatsApp or someone else were to access them, they would not be able to tamper with them.