Minic did three paddlers: Britannia (M728), 'Bristol Queen' (M729) & 'Cardiff Queen' (M730), The two 'Queen' boats were near-sisters, built after WWII. 'Britannia' was a much older vessel (1895), somewhat smaller & built with a single funnel but reboilered in 1948, emerging with two funnels. She was scrapped in the late 50s, the others survived until the mid-60s. (For what its worth, I get 240' for CQ & 244' for BQ [230' for 'Britannia]).
As Kelvin says, they were designed as toys, not precise scale replicas and would have been sold as such in the souvenir stalls onboard the original ships. If you compare them you'll see they have differing funnel colours.
TH