Sybil Tawse Pictures?

I bought these at an auction last night (£20 for all 4) I cant find any information about them online, was wondering if anybody could help with a value?

Here they are - The Sybil Tawse lithographs :D 'Spring','Summer','Autumn' & 'Winter' (in no particular order)

Spring?

Summer?

Winter

Autumn

Label on back of frames

If anybody could help, it would be great :D