Ball had added more than 200,000 listeners during her final year on the programme.
After taking over the breakfast show, Mills was replaced on his former afternoon slot by Trevor Nelson, whose evening programme was taken over by DJ Spoony.
Vernon Kay attracted an audience of 6.73 million in the first three months of 2025, meaning his mid-morning show retained its crown as the most popular radio programme in the UK.
The show is down, however, on the audience of 8.2 million achieved by his predecessor Ken Bruce, who left in 2023.