In article ,
says...
This plant was labelled with what I assume was a cultivar name - 'Gill
Lewis' - but didn't have any indication of what genus or species it
belonged to.

http://www.stewart.hinsley.me.uk/Images/GillLewis.jpg

Does anyone recognise it?

I am in agreement with Bob and Sacha achemines or streptocarpus a picture
of the whole plant would clinch it although I would favour achemines as I
feel you would have recognised a streptocarpus from its leaves. There are
no plants called Gill Lewis in the current plant finder so that is
probably the name of the person who raised it to sell it!
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea