It's common knowledge that Allan and many others drew inspiration and ideas from the American magazines of the time.
Here's the cover of Popular Hot Rodding from 1964 which had been reserved for Allan, you can see his name under the title.
The second image shows the shop where he must have got his mags from in Hayes. Interesting to see that you could get half price back on returned magazines.
I was recently kindly given these and other mags by somebody.
Most of them had the covers removed though.