One row per record query

Try the below:DISTINCT

select DISTINCT
P.ID
,P.dCreated as 'dtCreated'
,YEAR(P.dStart) 'StartYear'
,Month(P.dStart) 'StartMonth'
,day(P.dStart) 'StartDay'
,P.dStart 
,P.dEnd 
,DATEADD(YY, 1, P.dStart) as 'dtRenew'
,P.PolicyNo 
,C.Name 
,DC.Email 
,P.NetPremium 
,cast(P.Excess as decimal(18,2)) as 'Excess'
,cast(P.GlassExcess as decimal(18,2)) as 'GlassExcess'
,A.Address 
,A.Town
,A.PostCode 
,cast(P.GUID as varchar(50)) as 'PolicyGUID'
,cast(V.GUID as varchar(50)) as 'VehicleGUID'
,V.RegNo 
from dbo.Policy P
Inner join dbo.Company C on C.ID = P.HolderID 
Inner join dbo.Contact DC on C.PrimaryContactID = DC.ID
inner join PolicyCover PC on PC.PolicyID = P.ID
inner join dbo.Address A on A.ID = DC.AddressID 
inner join dbo.Vehicle V on V.ID = PC.VehicleID 
inner join
(
        SELECT MAX(ID) AS MID, PolicyID FROM dbo.PolicyCover GROUP BY PolicyID
) PC2 ON PC.ID = PC2.MID