Paul wrote:

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a
higher position.

One option is to mount it above the TV aerial, I understand that the
signal radiation below the antenna is very small, does anyone have any
experience of a similar setup? ...

I've been set up like that for several years with an X510. It's mounted
on the top of the same mast as the TV antenna with the TV antenna about 3
ft below the X510. It's all mounted on my chimney about 25 ft up. I run
9913 inside the mast to the X510 (the X510's base fits nicely inside the
mast). The TV antenna is an el-cheapo Radio Shack (Tandy) unit fed with
RG-6 running down the outside of the mast. I have no problems with it
running up to 50W on 2M and about 35W on 70cm. There's no interaction
that I can see...no problems with TVI or anything...works quite well.
This is in the US...not sure if it would be different in the UK, perhaps
due to different TV freqs???

73... Mark AA7TA