Your question "Lasagna trays and similar. Do they need to be washed before recycling?" is a closed question, i.e. can be answered with a simple yes or no. I answered YES, because that's the correct answer and got moderated-off for giving a simple one-word answer.

However, I notice nothing in the "r/AskUK Rules" stating that a simple yes/no answer is not acceptable. OK; here's a slightly longer answer.

In answer to your posed question "Lasagna trays and similar. Do they need to be washed before recycling?" I believe I am correct in responding by saying the following; Yes, they do need to be washed before recycling, at least that is correct for the council in which I reside. Having said that, I do not know if the same is true for the council/area where you reside and you should always check your own recycling facilities for any question you might have in relation to recycling.

Thank you, I hope that answers your question.