Yes, there was a milk bar close to the Capitol cinema. It was owned by a lady called Mrs Ball and, you're right - the milk shakes were delicious. That row of shops had Arrowsmith's (sweets and tobacco), J House (bread and cakes), the Milk Bar, Home & Colonial Stores and Freeman Hardy & Willis.
Opposite were Clarkes (butchers), T Mayne (bread/groceries), Hawtins (records and sheet music), Galpins - my grandfather and father - (hardware and petrol sold over the pavement), Tozers (butcher), Sands (grocers), Pets & Gardens(speaks for itself), Cookes (optician) and Midland Bank.
This was in the 1950s.
Actually, the best milk shakes were at Gardners Milk Bar, adjacent to the Beaufort cinema at the far (out of town) end of Alum Rock Road