Help me find this book please!!!

[Whatthefunk]

I put in books, but no luck, so trying here, because it's driving me crazy!!
So I read this book , when I was about 11. So about 40 years ago....I can hardly remember anything, but it's driving me nuts.... boy looking out of the window, and see a lorry and men acting strangely....think there is maybe a robbery. The lorry is referred to as a pantechnicon....this is all I have...help!

To add, it's set in England, and is quite dark. I read a lot of Honor Arundel books, in my childhood, so maybe a similar feel to that, but I don't think it's her...

Doing a quick google is it The Pantechnicon by Lionel Miskin. Was published in 1971

Oh my goodness, no it's definitely not that...I wasn't really into erotica as a child

Haha! Just thought I'd say in case

I'll keep looking!