Harold didn't exactly feel uncomfortable out of his comfort zone of Knockturn, but Diagon was so bright and sunny and good that it was almost creepy. There were little kids smiling and families wandering around shopping for books and pets and shit. At least people were real down Knockturn, he understood what was going on, he knew who to be wary of, who were allies and who would slit your throat for your wand. There were rules and codes. Diagon felt fake, and distinctly tinged with the Ministry's pallor. In fact, as he made his way to Fortescue's, it was like walking through a Ministry propaganda poster - 'Look how wonderful Wizarding Britain can be!'.
It made him shudder.
He hadn't dressed up, so whoever Lavender Brown was, she shouldn't expect anything much. Scuffed boots, possibly clean trousers of a brown or beige colour, and a dingy blue vest because it was a bit warmer today. Smirking at a mother who tugged her son closer to her as Harold leaned against the wall outside the ice cream place and lit up a cigarette with his wand, he lazily ran his gaze along the crowd, waiting for this chick.
He hadn't admitted to being able to get the ingredients in the journal, so if she did turn out to be MLE, he didn't have anything to worry about there. But he'd had the Ministry try to catch him out before, and they usually wanted to meet in Knockturn, some sort of show of intent, but Lavender Brown wanted to meet at Fortescue's. She was either MLE trying something different, or a genuine potential customer. He'd know soon enough anyway.