now you come to mention it I havent. the catalogues I've seen are all for the large tuberous ones.
Ah Parkers have begonia illumination apricot shades maxi plugs 33 for 9.99
and they also have jumbo plugs of begonia million kisses 3 colours 6 for 9.99 or 12 4 of the 3 colours 15.98

Parkers can be a bit hit and miss with their plugs but their corms tend to be of a good size and I have had good results with them.

I get my begonia plug plants from Dobies (Devon) - www.dobies.co.uk - they have both bedding and tuberous begonias. I have always been very pleased with the quality of their plants.

Big Begonia are best from tuberous Begonia types. Larger the tuber, the larger the plant. Plug plants, one assumes, are from seeds.

some are rooted cuttings in the larger plugs and they do flower well.

I am actually looking specifically for the 'Big' series of Begonias.

Latin name: Begonia x benariensis 'Big'
Common name: 'Big' begonia
Flowers: Red or pink
Foliage: Green or bronze glossy foliage
Mature height: 18" x 18"
Hardiness: Summer annual
Soil: Well drained
Exposure: Full sun to shade
Water usage: Medium

First saw them three of four years ago, pretty sure from Fothergill. I had them two years running and they were healthy, vigorous and covered in flowers. Look like a large, robust Begonia semperflorens.

your lucky then bilbo. the only plants i got from them were appalling.

Jersey Plant Direct is not a company I have tried, so thanks for suggesting them. I am not too put off by mixed reports as I have had some good and bad from the best of them, so if they have the right begonias, I would give them a go.
Thanks