The late Neil Williamson once used a memorable phrase to describe what he saw as the SNP’s lack of political imagination.

Noting the tendency to present independence in wholly uncritical terms, Williamson derided the belief that Scotland could somehow free itself of all the UK’s problems simply by “rearranging the furniture”.

He wrote those words almost exactly 40 years ago, but it’s as true today as it was then. Take the current – and typically sterile debate – over the (far from) great repeal bill and whether or not it constitutes, as the First Minister claims, a “power grab” by Westminster.

On that, the Scottish Government has a point, although what I find more interesting is that ministers in Edinburgh appear more preoccupied with where such powers lie rather than what they’d actually do with them.

Power over agricultural subsidies – distributed via the Common Agricultural Policy (CAP) – is currently “shared” between Brussels, London and Edinburgh, although once the farcical Brexit process concludes in 2019, then the first of that trio will be removed. Edinburgh’s ability to tweak local application could be eroded in London’s favour.

So, the SNP says it should have all the power and, naturally, the funding to match. Beyond that, however, it isn’t clear how much thinking St Andrew’s House is doing on what replaces CAP in two years’ time.

The relevant section on the SNP website is typically broad brush, calling for “all payments” to be “guaranteed” by the UK Government until the end of the current CAP payment period in 2020. And, it adds, since support for farmers will still be required beyond 2020, “there should also be a guarantee that funding will be provided” after that point.

As usual, the Scottish Government is channelling Boris Johnson in being both pro-cake and pro-eating it. In other words, instead of thinking “radical” thoughts, it’s proposing little beyond a rearrangement of the constitutional furniture.

The Conservatives, meanwhile, display their own contortions. Witness Ruth Davidson at First Minister’s Questions skewering the Scottish Government over botched CAP payments and you’ll see a Conservative, who apparently believes in self-sufficiency and free-market economics, defending subsidies that far outstrip anything going to benefit claimants.

Naturally, there are powerful vested interests at work. Just as the SNP once enjoyed an overly cosy relationship with the National Farmers Union of Scotland (NFUS) – its policy director was even embedded in the Scottish Government – now that rural Scotland has once again turned blue, the Scottish Tories are trying to consolidate their position.

The new Scotland Office minister Lord Duncan (who has a fisheries background) is clearly central to that process, and the UK Government is conscious there exist what a source calls “material differences” between what the Scottish and UK NFU want to get out of Brexit. Both the Conservatives and SNP, however, ought to view this as an opportunity to pursue a long-delayed overhaul of CAP which, after all, will soon no longer apply.

At present, CAP is worth about €408 billion, or almost 40 per cent of the entire European Union budget, of which almost three quarters goes on “direct payments” to support farmers (Pillar 1), and the other quarter on sustainable rural development (Pillar 2).

Its weaknesses, however, have been widely catalogued, not least a disproportionate benefit to farms with the biggest incomes. Some estimates suggest around 20 per cent of the recipients reap roughly 80 per cent of direct-income support. In 2013, the Scottish Government directed £3,226,492 towards a single so-called “slipper farmer”, who’d “gamed” the system by buying “entitlements” from retiring landowners.

In Scotland, for example, the amount of farm subsidy paid to the top 50 recipients increased from £22 million in 2008 to £24m in 2009, £27.6m in 2010 and £35m in 2011. Now given that farming isn’t a typical “industry” few would argue it doesn’t deserve financial support, but it’s much harder to defend a system that does little in terms of encouraging farmers to manage resilience, sustainability or innovation.

As Pete Ritchie (of Nourish Scotland) argues in a new book on “Scotland, the UK and Brexit”, more than half Scotland’s farmers voted for Brexit. “They wanted the future to be much like the past, same money but with less paperwork.” Indeed, they’d rather some of the qualifying conditions, such as three-crop rules for Continental farms, were done away with.

There have been previous attempts at wholescale reform. Back in 2005, the then Chancellor Gordon Brown warned France that it must agree to significant reform of CAP if there was to be any chance of securing a deal on the EU’s long-term finances. In 2011 David Cameron also had a go, making the reasonable point that with global food prices at record highs then subsidies ought to be at all-time lows.

Although CAP was reformed – the overall budget was cut and farm payments capped – the new Basic Payments System introduced in 2015 (which awarded a fixed payment per hectare of land farmed) created its own inequities, in some cases quadrupling subsidies to farmers who freely admitted they didn’t actually need the cash.

Scottish farmers generally do well out of the current CAP system (a few years ago they received the second-highest average payments in the EU), thus why the former Scottish Tory MEP Struan Stevenson recently warned of a Brexit-induced “meltdown” in rural Scotland with cheap food imports pushing farmers out of business (although he, like the SNP, wants the UK Government to guarantee subsidies beyond 2020).

Pete Ritchie suggests an agricultural policy that “aligns farm support much more clearly with progressive policies on land reform, climate change, biodiversity and public health”, and indeed Brussels is already looking at further reform likely to involve a serious budget cut and additional responsibilities.

The current Rural Affairs Secretary Fergus Ewing isn’t exactly known as a left-wing radical, but he ought to at least try and resist the inevitable pressure from the NFUS to protect its members’ interests (or rather its biggest members’ interest) and propose – in tandem with London – a more equitable regime. The Scottish economy isn’t out of the woods yet, and innovation ought to be encouraged.

It could always form part of the Scottish Government’s “relaunch” this autumn: what better way to indicate that the SNP is finally willing to take on vested interests rather than just rearranging the furniture?