create view RecordYearsTwo as
select Record.RecordID, RecordValue.Value
from Record join RecordValue on Record.RecordID = RecordValue.RecordID
where len(RecordValue.Value) = 4
and RecordValue.Value like '[16-20][0-9][0-9][0-9]%'
and RecordValue.Value like '%[16-20][0-9][0-9][0-9]'
and RecordValue.Value != '26 Mar 1850';

select * from Record
join RecordYearsTwo on Record.RecordID = RecordYearsTwo.RecordID
where cast(RecordYearsTwo.Value as int) >= 1800

Conversion failed when converting the nvarchar value '26 Mar 1850' to data type int.

create view RecordYearsTwo as
select r.RecordID, v.Value
from Record r
join (
    select *
    from RecordValue
    where len(Value) = 4
) v on r.RecordID = v.RecordID
where len(v.Value) = 4
    and v.Value like '[16-20][0-9][0-9][0-9]%'
    and v.Value like '%[16-20][0-9][0-9][0-9]'