Mrs Burns' Lemon Basil is a popular herb known for its citrusy fragrance and flavor. However, if you are unable to find this specific type of basil, there are some alternatives you can try. Lemon Thyme, Lemon Verbena, and Lemon Balm have similar citrus notes that can be used in place of Mrs Burns' Lemon Basil. Additionally, Thai Basil and Lime Basil have a slightly tangy and distinct flavor that can work well in dishes that require a lemony kick. In case you can't find any of these herbs, you can also use regular basil and add some lemon zest to get that bright, zesty flavor.