Anyone know good stockist of plus size summer dresses?

[Biglaugh]

I am looking for a size 20 button down, cotton or polycotton midi dress with half sleeves to wear for work.
I realise I am a throw back from the 1980s but I have a dress like that and it is perfect, it has a tie at the back and it is not too shapeless but covers large legs/arms/belly without looking like a tent.
Before I take the only dress I have to a dressmaker can anyone help?
I have tried Googling every combination but there is nothing out there
Can you help please??

I am having a wee bit of trouble picturing the dress but anyway - M and Co have some gems in occasionally, worth a look...

www.forever21.com/UK/Product/Product.aspx?Br=f21&Category=DRESS&ProductID=2000077571&VariantID=&utm_source=0RpXOIXA500&utm_medium=affiliate&utm_campaign=linkshare_f21

Like this but with sleeves.
Thanks so much for looking DonkeyOaty. I will try M and Co

Bon prix [[www.bonprix.co.uk/products/Button-Through-Maxi-Dress/_/A-972791_10 viscose though]]

Found by searching "button through" as opposed to "button down"

You are some sort of genius Thank you

And DonkeyOaty, if it is too long I can try and shorten it using the mini sewing machine I bought in the pound shop, which so far I have been unable even to thread.
The model looks spookily like me...

Hurrah!