Derwentside's Joanne Jackson finished her heat in 4:04.81 and it looked clear early on that the athletes were going to come close to the Commonwealth record of 4:04.50. British Champion Adlington positioned herself behind Jackson for the first 150m and looked comfortable with the high pace.
Both athletes were turning well within the British and Commonwealth record, which Adlington set at the British Championships in April, at each junction and Adlington made her move for the lead at the half way mark.
Adlington stretched out her lead in the final 50m and touched in a time of 4:02.80 to become the third fastest woman this year and fourth fastest woman in history over the distance.
"That was unbelievable," Adlington said. "I don't understand how I've just done that time. I've been training really hard throughout this meet, doing 7km a session and then trying to race hard through it.
"I felt awful this morning. I've been sluggish and heavy through the water and I didn't think I could go that fast. I expected a 4:08 and would have been happy with that."
The silver medal went to Jackson in a time of 4:05.49 with Swansea Performance's Jazmin Carlin winning bronze in 4:16.79. Camelia Potec of Canet 66 won a commemorative medal in 4:08.72.
Jemma Lowe (Borough of Stockton) swam just outside of her British record in the women's 200m Butterfly final.
As they turned for the final 50m Lowe was on half a second off her record and she looked strong as she swam into the final 25m. She touched in a time of 2:07.57 to win the gold medal after just missing her record.
The silver medal was won by Lowe's club-mate Jessica Dickons in 2:08.74, while the bronze went to Derwentside's Stephanie Johnson in 2:13. 76.
