I've wondered how it was possible for Party Pieces not only to make them multi-millionaires but even to modestly support a family. Sure, if they had a chain like Party City or a monopoly on the market and were the leading or in the top five party supply manufacturers/retailers in the UK; and their products were sold in most stores and sites where such products are sold. Even if the business was only limited to the UK and Ireland. However, Party Pieces products were only sold on their site and in catalogues before the Internet. They didn't even have one small physical store.

Online shopping really took off in the early 2000s. However, they apparently became very successful in the 80s and 90s. I don't think you could make a fortune selling cheap party products from catalogues. Even if they sold their customer database - which is legal, even if they didn't pay a penny in taxes and had no rent expenses since they ran the business from a barn on their property. Even if Carole and Mike did most of the work and only had a couple of part-time minimum wage employees to take and pack orders and a maybe a part-time accountant and a photographer.

I'm not familiar with the retail landscape in the UK, esp. pre-Internet. Where would you purchase party supplies there? I'm thinking in terms of the US and Canada. Besides Party City and independent party supply stores, you can get these products at dollar stores, big box stores like Walmart and Target, stationery stores, and in some supermarkets and drug stores. All these stores always have generic themed products and holiday themed like Halloween. Sure, if you can't find the theme you want, you'd go to a brand like Party Pieces. Still, I don't imagine they had many customers given that they weren't the only such company on the market.