It'd take your nan ages to knit something like this, get it on a t-shirt instead! This Navy and Red one to be precise! 

• Made from a polyester yarn that has been specifically developed to have the touch, feel and breathability of pure cotton, woven here in the UK. Compared to cotton it is much more sustainable and uses a fraction of the water in its production. It’s also vegan friendly.
• Made in England
• Regular Fit