According to MobileFun the UK release dates for the Nokia Lumia 900 and Lumia 610 have been uncovered.

The Lumia 900 is scheduled for launch on April 9th, while the Lumia 610 is believed to become available on June 11th.

There is no real source behind these date, just the result of “some digging” that MobileFun did, so take these dates with appropriate caution.