The China Roses
These tend to have smooth leaves, not many prickles and flowers with thick petals and not very much scent.
They are an important group because they flower continuously and this characteristic was crossed with European roses in the 18th century to create the beginnings of the repeat flowering roses we have today.
Several China Roses are grown in the park, principally in the Tea and China bed.
Look for Old Blush, Comtesse du Cayla and Mutabilis