A SURE sign that we're in the throes of the summer silly season is when photos of political leaders holidaying in sunny climes begin appearing on newspaper front pages.

Just days into the Westminster recess, Theresa May was captured in assorted snaps seeking some holiday R&R in northern Italy after a torrid few weeks.

Doubtless we will get equivalent images of Jeremy Corbyn at some stage and perhaps Nicola Sturgeon, although Holyrood has already been in recess for nearly a month - and anyway the SNP leader tends to be more circumspect than her Westminster counterparts in such matters.

What's striking about this year's break is the sheer scale - even compared to previous troubled times - of the unresolved issues and tensions that all the main parties face to a greater or lesser extent, most notably over Brexit in what promises to be a cruel summer.

May and her acolytes displayed the same eagerness for the arrival of Westminster's summer recess as a boxer taking a battering from a rival pugilist in a one-sided title bout who is anxious for the bell to sound to allow for a few precious moments to regroup.

With Brexit negotiations rumbling on throughout the summer and the prospect of murmurings over May’s leadership following the loss of the Tory overall majority, there’s every chance we could see one of the most troubled summers for a UK prime minister in a quarter of a century.

It's often summer parliamentary hiatuses that make matters considerably worse for a PM as John Major found out back in the summer of 1992 when, fresh from an unexpected election victory, serious discontent festered among Tory MPs about closer European integration through the Maastricht Treaty signed a few months before.

Although very different circumstances, the schism laid the ground for internecine Tory infighting over Europe in the early and mid-1990s, from which Major's ill-fated government never really recovered and in which today’s Brexit is arguably rooted.

There’s also always the chance that this summer’s talks in Brussels could collapse, triggering a recall of the Commons.

It’s clear that May’s cabinet is divided over just how hard a Brexit deal should be negotiated, with Chancellor Philip Hammond and Foreign Secretary Boris Johnson, as well as the more hardline Trade Secretary Liam Fox, reported to be at loggerheads.

Again the summer months also give Tory MPs, some of whom perhaps believe they were sold a pup over May’s leadership qualities a year ago, a chance to plot and position themselves for a tilt at toppling the PM.

When the Tories gather for their conference this October in Manchester, a city in which they have not had an MP since 1987, tensions could rise in temperature as happened to Major in 1992 when civil war over Europe erupted at the party’s annual gathering that year after a summer of simmering resentment.

Even in this era of more stage-managed party conferences there's still the potential for trouble - despite it being behind the scenes plotting in conference bars and gripes at fringe meetings about the PM, whose claims of strong leadership are not helped by having to rely on Northern Ireland's Democratic Unionist Party to sustain her in power.

A bad conference for May after a difficult summer could put her on the same road as Major, who while remaining in power for five years partly due to an informal pact with the Ulster Unionist Party, limped from crisis to crisis, before being defeated at the 1997 election.

There are also potential pitfalls for Jeremy Corbyn over the summer and at Labour's conference in Brighton in September, despite the unexpected loss of the Tory overall majority and the first election that Labour has increased its Westminster seats at since 1997.

While not on the scale of the difficulties facing May there has been opposition from some Labour backbench MPs to Corbyn’s backing for what some see as a left-wing version of Brexit.

True, part of this opposition comes from New Labour ultras who would happily seize on any issue to vent an unspoken frustration that Corbyn did not crash and burn as they had predicted.

At the same time there is a degree of uneasiness this summer over the Labour leadership's Brexit stance among some of those pro-Europeans not necessarily universally hostile to the Corbynite project.

Corbyn’s internal enemies will almost certainly use the autumn conference to make more pronounced claims that Labour did not do as well as is being feted by some and could have fared much better than the 30 seats gained by the party given the incompetence of the Tory campaign.

Such claims are in truth a moving of the goalposts from the dire warnings issued by Corbyn’s internal opponents before the election that Labour was facing a 1980s-style hammering and possible electoral oblivion.

But revisionist swipes of that nature and the Brexit disagreement among Labour MPs will not be helpful to Corbyn, who nonetheless is secure in post and likely to receive a rockstar-style welcome at his party conference akin to the one he enjoyed at the Glastonbury festival.

The SNP, of course, on the whole doesn’t do summer squabbling or public bickering at any time of the year for that matter.

Nicola Sturgeon is as equally secure as SNP leader as Corbyn is as Labour's despite her party's loss of 21 Westminster seats, the inevitable consequence of which saw her put her independence referendum plans on hold.

But despite the likelihood that Sturgeon will remain First Minister for the foreseeable future, some SNP supporters may be thinking over the summer that their party could be on a slow burning downward spiral for the first time in over a decade.

It’s unlikely such concerns will manifest themselves too publicly, with the big beasts who lost their Westminster seats such as Alex Salmond and Angus Robertson being arch-advocates of the SNP’s iron-like approach to discipline.

With the referendum plans on hold, the party leadership’s thinking appears to be personified by that of Robertson’s successor as Westminster leader Ian Blackford who says in this week's Sunday Herald that the focus now has to be on making the case for independence afresh.

It’s a strategy that Blackford suggests could mean the rebooting of the arguments for independence, centred around a social justice and fairness agenda.

Such a platform may be something that gives the SNP faithful fresh impetus after a summer of reflection on the party's electoral and referendum reverses.

Blackford's call may be something to watch out for at the SNP’s conference in Glasgow this October when members could be looking for a new way ahead after a bruising summer.