Something to wear over a navy dress?

[DailyFailAteMyFish]

Hi,
I have many dresses like this:
m.boden.co.uk/en-gb/womens-dresses/smart-day-dresses/ww118/womens-honor-dress
That are navy. Also many dresses in slightly different styles that are navy (navy suits me and I'm a creature of habit).
I also have an office that has incredibly powerful air conditioning in the summer so I need something to wear on top of the dresses.
Work is too casual for blazers. I feel cardigans are too mumsy but I currently wear them in grey or ivory.
Uniqlo had a cardigan/blazer that looked nice, but them I remembered I wore something like that befote and felt even more mumsy.
Are cardigans the only way?
Or am I missing something?
Or I could just buy dresses with sleeves...
Thanks!

[HappyMedium]

I also have lots of navy dresses. Like you, I'm not a cardigan lover. But I do have several bolero type cover ups from the likes of Monsoon in bright colours like pink and yellow. They're fairly plain with no buttons or frills etc. They're comfy and less restrictive than jackets.

[DailyFailAteMyFish]

Ooo bolero type cover ups!
Thank you! I am off to google.