Blechnum chilense
Growing here in full sun and with occasional exposure to salt winds at Logan Botanic Garden on the west coast of Scotland , confounding the usual profile for this plant as a woodland specimen. Although it thrives in this garden, suckering and practically making a lawn, it does not grow such luxuriant fronds.
This plant is growing in central london in the Exotic Woodland In The City where it enjoys woodland conditions and the mild climate of a city centre. In the years after this photo this specimen reached about 80cm tall.
Left - of all the ferns that we can grow in the UK, this has the most tropical looking, with leathery fronds that remain evergreen in mild winters.