Thanks for the welcome to the forum, and all the replies.
The rack isn't level and sits on a slant. I have carried shopping in pannier bags which probably weighed 8-9kg.
Only yesterday, chatting with a neighbour, I was advised of a local metal fabrication business which is a 3 min cycle from my home! So, I'll pop down and ask if the pannier rack can be adapted. I'm unsure of the metal, but, I'm sure I'll be advised of same.
A couple of pics of Hollie, who had been with the SSPCA since April this year, having been neglected. She is 9 years old and was rehomed with me in September. She's a wee sweetie with a big personality!