I bring you one cunning trick to make adult shirts smaller for children!
Here's what to do:
1. Find suitable 100% cotton adult shirt. I used a men's work shirt with a 15" collar pilfered from Mr B.
2. Wash on it's own in the washing machine on a 90degC cycle with bicarb and vinegar. I used 3 tbsp of bicarb, which I put in the drum with the shirt, and 1 cup of spirit vinegar which I put in the soap drawer. This should cause the shirt to shrink a little.
3. Tumble dry on the hottest setting to make the shrinkage permanent.
4. Repeat steps 2 and 3 again until you have reached the desired size. I did about 5 repeats to make the shirt small enough for toddler - about a size 104cm (age 4-5).
After this, when you come to launder the shirt normally, just use non-bio soap powder and wash at 40degC with the rest of your laundry. Magic!
Only joking. Of course I didn't. I used this.