I would think that you can just create a formula which adds the appropriate amount of time to the create date (this assumes that what you're trying to say is that the data is NOT stored in UK time).
A SQL Expression might work, using:
dateadd(h,X,table.datetime)
Where X is the hours difference.
Keep in mind that the datetime stored may represent a changing datetime as a result of daylight savings, etc. over time, so you may need to increase your sophistication.
A Crystal formula can also do this, as in:
dateadd("h",X,table.datetime)
A simple hardcoding would be:
{table.datetime} > datetime(year(currentdate-2),month(currentdate-2),day(currentdate-2),19,0,0)
and
{table.datetime} <= datetime(year(currentdate),month(currentdate),day(currentdate),19,0,0)
Hope this helps.
-k