Election 2017: Does Plaid Cymru face a breakthrough?

"If not now, when" is probably a question Plaid Cymru activists should be asking themselves.

For the best part of 50 years Plaid have been hoping for a big breakthrough in industrial Wales, particularly the southern valleys.

Over the years there have been some close parliamentary by-elections, the odd assembly seat won and councils captured for single terms.

What has not happened is the sort of permanent political shift from Labour to Plaid that the party has yearned for for decades.

With Labour in meltdown, though, shouldn't the party be able to capitalise this time?

Probably not, if the polls are to be believed.

The problem may be that, in truth, there is very little difference between Plaid and Welsh Labour's offers to the voters.

While Plaid are, to use their campaign slogans, "Defending Wales", Labour are "Standing up for Wales".

On the key issue of Brexit, the two parties signed up to a common policy.

The real point of differentiation, of course, is independence - and there aren't that many people in Wales who think that's a good idea.

As in the local elections, Plaid could end up making gains this time.

As for that elusive breakthrough though, well, don't hold your breath.