The Sheffield 23-year-old, who is now based in New Zealand, took gold in her second British record of the day as she touched in 31.40 seconds, 0.9sec ahead of her principal rival, Agnes Kovacs of Hungary, who beat her narrowly at the European Championships in Istanbul last summer.
Baker said. "I had a slow turn - in fact an awful turn - and that probably cost me a European record."
Margaretha Pedder was also in record form, the Portsmouth swimmer breaking her own British mark in the women's 200m butterfly final. Pedder finished fifth in 2min 9.56sec.
Ed Sinclair finished fourth in the 200m freestyle final, again in a British record time. James Hickman qualified for today's 100m butterfly final, Sue Rolph qualified second-fastest for the 100m freestyle final and Katy Sexton and Sarah Price reached the 100m backstroke final.Reuse content