C# Given a custom class and custom attribute how can you find the attributes of a class from the base class

Given the following class

[KeyField("dap_name")]
public class nhs_acquisition_profile
    : DALObject
    , IDisposable
{
    public nhs_acquisition_profile()
        : base()
    {
    }

    public nhs_acquisition_profile(String ConnectionString)
        : base(ConnectionString)
    {

    }


}

How could I find the value of the KeyField Attribute but from the base class.