Since my last post, I found a couple more pics, including the one you posted, showing the vertical dipoles. But, the majority are angled, and are shown like this on scale plans I have.
Note that your second pic is the earlier set-up, with the central antenna also, and this was vertical. The third pic, I think they may be angled, and the RAFM example not quite accurate. I have read that, when it was refurbished and moved from St.Athan to Hendon, apart from the slightly incorrect re-paint, the antenna were incorrectly re-assembled.
The final pic I thought was the RAFM example in its original paint finish - but it appears to have the early, central antenna as well as the large 'antlers', so again, a slightly different set-up.
I'd need to find the info, but, as previously mentioned, I think the change of angle was to improve reception.