Boris Johnson is “mortified” after breaking Covid rules by having had a birthday gathering in the cabinet room but is “human”, one of his cabinet ministers has said. Grant Shapps, the transport secretary, was sent out to defend the prime minister after Johnson and the chancellor, Rishi Sunak, were given fixed-penalty notices by police. He said the prime minister was sorry but went on to minimise the event by saying Johnson had just “walked into a room” where people were gathered to wish him a happy birthday for 10 minutes. Shapps insisted Johnson acted “without malice” and did not “knowingly break laws”. The cabinet minister said he was simply meeting with other people he had seen for work purposes earlier in the day – although this contradicts reports that his interior designer Lulu Lytle, who was carrying out renovations in No 10, was also present. Johnson’s wife, Carrie, who was also present and has been fined, has apologised. Speaking on BBC Radio 4’s Today programme, Shapps urged people to “judge him in entirety” and look to Johnson’s record on Covid, the approach to the Ukraine war and economy. When asked how it had not occurred to the prime minister that he was breaking the rules, Shapps told BBC Breakfast: “I don’t seek to say anything other than it’s deeply disappointing. Of course, it should have done. “I think in answer to your question, specifically, he will have already been in that room with the same people that day chairing crisis meetings on the world’s biggest pandemic for over 100 years. “And he walks in by surprise and into the same room to the people who wished him happy birthday on this occasion. And that’s of course the thing which breached the law, and the police have ruled on that and he has paid the fixed penalty notice of £50 and apologised.” Johnson and Sunak are believed to be the first sitting prime minister and chancellor to be criminally sanctioned. Both senior politicians were also accused of misleading parliament by previously denying they had attended parties during lockdown. Keir Starmer, the Labour leader, called on both the “guilty men”, Johnson and Sunak, to resign for “dishonouring their offices”. He said Johnson had “lied repeatedly to the public” and his behaviour was a “slap in the face” to all those who had followed the rules. “They have to go,” he said. Labour and the Lib Dems backed calls for a recall of parliament to discuss the penalties but that is likely to be blocked by the government. The notices put Johnson’s leadership in renewed trouble, although allies including Nadine Dorries and Conor Burns rallied round him by issuing supportive messages. Liz Truss, the foreign secretary and a potential future leadership contender, also issued a supportive statement, saying Johnson had “apologised and taken responsibility for what happened in Downing Street”. “He and the chancellor are delivering for Britain on many fronts including on the international security crisis we face. They have my 100% backing,” she said. Some Conservative MPs previously suggested a line would be crossed by allowing a prime minister to remain in office if he was found to have broken the law. About 20-30 MPs were at one point thought to have submitted letters of no confidence in the prime minister, with 54 needed to trigger a leadership challenge. However, many of those who had previously submitted letters of no confidence – Sir Roger Gale, Andrew Bridgen, and Douglas Ross – said now was not the time to change leader given the instability caused by Russia’s invasion of Ukraine.