Greenbank finished in a time of 1:55.34 to shave 0.24 seconds off James Goddard’s long-standing record.
The 24-year-old finished the race 5.30 seconds ahead of his nearest rival as Loughborough’s Elliott Clogg touched the wall in 2:00.64.
“I’m over the moon with that! I came into this meet wanting to build on the last one and to do that in the heats gave me great confidence for the final,” commented Greenbank.
“I’ve had my eyes on this one for a while, but I didn’t think I’d break it in-season, I thought it’d be at trials where I could have a go at it.
“It feels absolutely amazing, and obviously it was James Goddard’s record before this and as a kid I watched him swim at an international level, so was he kind of an idol of mine, so to get that record is amazing.”
Elsewhere, Loughborough swimmer Molly Renshaw was only seven-tenths outside a new British record in the Women’s 200m Breaststroke.
Renshaw finished in 2:22.78, just 0.70s adrift of Loughborough’s Jocelyn Ulyett’s 2017 record of 2:22.08. Ulyett performed well in this race too; finishing second with a time of 2:26.19.
Adam Peaty continued his fine form in the Men’s 100m Breaststroke, edging out James Wilby in a time of 58.52. Wilby finished just behind, recording a time of 59.31.
It was also a fruitful weekend for another Loughborough athlete as Joe Litchfield recorded a new personal best in the Men’s 100m Butterfly with a time of 52.86.