Advice please on where to buy 'larger' boys clothes

[geekyboo]

Hi, so I'm new to this site guys and I'm not a parent but instead an aunt so I hope this thread is in the correct place. My fiancé an I are getting married in July and our 5 year old nephew (on his side) is going to be over from the USA to be our pageboy. Despite being only 5, our nephew is the height of an average 8 year old and according to UK sizes the waist measurement of a 13-14 year old, so as you can imagine I'm in a small predicament as to where to find him smart trousers/shorts to fit him. I really don't want any shaming or judging going on, (there are many complex reasons as to why things are the way they are) and to pass these comments is unhelpful to everyone. Does anyone have any advice or previous experience of shops/online sites that've been helpful?

[geekyboo]

Thanks VocationalGoat, I did see the sturdy kids website. Its good to get recommendation though. I've also come across Gary's Generous Fits on Ebay with 100% positive feedback. Was wondering if anyone had heard/had experience of them?