Old lead valley guttering on skate roof, sandstone property.

Is there any sign of water ingress around where the valley is? The best way would be to inspect the lead at close proximity. If its still dressed firmly to the valley board underneath and there are no holes in it then its working fine. Provided your building isnt grade 2 listed or on some kind of preservation order you can use fibreglass valley troughs now. They come in 3m lengths at around £15 per each which is far cheaper than lead and also comes with a 25+ year manufacturers guarantee.

in answer to your question no, lead is by far the best product for the valleys but like everything else in life if you want the best it costs. I spend a lot time replacing leaking fibre glass valleys. but if your valley is not leaking leave it alone. good luck Alex