Coach McCullum happy with England progress but side not 'finished article'
England swept the three-match series against the West Indies on Sunday as they won the final test at Edgbaston by 10 wickets inside three days.
"I thought, overall, it was a progression of where we wanted to get to as a team. We're not the finished article. We know that," McCullum said.
"But I think this series has been a step forward for us. It has been a while for us to get a series win and we'll never take that for granted."
England last won a series away against Pakistan in December 2022, followed by a draw in New Zealand, a tied Ashes series last year and a 4-1 loss in India at the start of 2024.
They are next up against Sri Lanka at home, with three tests starting late next month, where England will look to hone an exciting looking pace attack.
Mark Wood took five wickets to rip through the West Indies innings and set up the win on Sunday while Gus Atkinson was named man of the series after taking 22 wickets in his first three tests.
"He's moved the ball off the seam both ways, hits great lengths, bowled high pace and committed to the bouncer plan and done what the captain asked and sustained it," McCallum said of the 26-year-old test newcomer.
"He's been outstanding and he's quite cheeky within the group too and the guys love him."
"It was a pretty slow wicket but we showed that we had an attack that could expose different options," added captain Ben Stokes of the Edgbaston surface.
"Whether it was when it was reversing, when it was swinging or when it was very flat, we had an attack that could try and change the momentum of the game.
"Having different types of options in your armoury in a bowling attack is obviously key, especially when it's flat, when it's not really offering you much in the air or off the wicket."
"Having Mark Wood and Gus in this game in particular I think was very good and obviously having those two operate together is very, very exciting for the future of England," Stokes added after smashing the winning runs on Sunday.