Johnson Bros Windsor Ware Yeovil Pattern 12 place dinner and tea set

I have a Johnson Bros Windsor Ware Yeovil Pattern 12 place dinner and tea set purchased by my late mother in 1951 from Harrods It contains plates (dinner, tea and side), soup bowls, 3 platters,  3 terrines ,cups (tea and coffee), saucers ,jugs, teapot and sugar bowl, in all well over 100 pieces most in pristine condition.

I see people sell the plates for £5 and the larger items for £20 on E bay. i have no idea how much the set is worth. can you advise

I have attached the original bill and one item so you can see which pattern it is.

 thank you