I got an email from Kate Grundy who asked me how to go about doing top-ups for mobile phones. 

She isn't a retailer but her mum is. Mum only takes cash at her shop (Maggie's General Store in the West Midlands) but she has been asked by quite a few customers for top-ups. "I'm not sure how you would go about providing this service and my mum is also concerned about the financial outlay," she wrote.

She also sent me a lovely picture of the traditional brick-built shop and a list of its offerings. It might look quaint, but it does the lottery and stocks an impressive array of product categories including: delivered fresh bread and milk; confectionery galore; chilled drinks; cut meats; greetings cards; household; hosiery and toiletries; stationery; and, best of all, also acts as an Avon representative.

Maggie's can, of course, get a free terminal from Epay which will pay varying commission on phone top-ups, credit card payments and congestion charging on a minimum transaction level of £750 a month.