There is a saying that "what goes around comes around".

And so it is with the highly orchestrated attack on the PCS union.

On Newsnight on November 30, 2011, PCS general secretary Mark Serwotka calmly and patiently took apart the Government case for making public-sector workers pay more and work longer for a poorer pension. His opponent in the studio was Minister for the Cabinet Office, Francis Maude - not an easy figure to walk over. Serwotka did the same thing to Maude on the same issue on Radio 4 on June 30, 2011. This is testament to the PCS being the most articulate, credible and consistent critic of the Government policy of austerity.

As Minister for the Cabinet Office, Maude is in charge of relations with civil servants and their unions. With no doubt an extra element of personalised vendetta involved, Maude has overseen a four-pronged attack on the PCS. The ending of check-off is by far the most serious as it seeks to undermine the financial viability of the union to exist and operate. Effectively, this means trying to silence the PCS, forcing it to concentrate upon its own internal affairs to the detriment of anything else.

The other prongs of the attack are reducing facility time for union representatives, encouraging alternative moderate unions and refusing to engage in meaningful negotiations.

For many years, reps in public-sector and civil service unions have been given time off during working hours to carry out their union duties. The most senior reps - like national executive members - have been given full-time release. PCS is the only public-sector union to have been consistently targeted by the Westminster Government since 2010 with reduced facility time in the civil service. By contrast, the current Holyrood Government has supported the continued use of proper facility time for PCS reps in the Scottish civil service.

In HM Revenue & Customs (HMRC), management has signalled its intention to marginalise PCS because of its continuing opposition to service cuts and closures. This involves "proactive measures targeted at key union activists", according to the leaked HMRC document, and encouraging staff to join a new union, the Revenues and Customs Trade Union. Similar things have taken place elsewhere in the civil service, namely the sacking of union reps and a breakaway union being formed in the Serious Organised Crime Agency.

And, in an attempt to bolster existing, more moderate unions in the civil service, the Government has also effectively sidelined the PCS from negotiations over changes to civil servants' terms and conditions. That is part and parcel of why the PCS union has been at the forefront of deploying industrial action to defend its members' interests.

This is quite a different strategy from that applied to Unite. As it is the main union affiliate to Labour, the Conservatives have targeted Unite as a "malign" influence on politics. And because most of Unite's members are in the private sector, it has also targeted Unite's "leverage" strategy of public protestations against companies like Ineos.

But what is common to the different strategies is that critical union voice is to be denigrated and union capacity degraded.

With the Conservatives determined to continue to use the opportunity of austerity to permanently shrink the welfare state, the PCS is one of the few major voices to not only stand out against this destruction but also put forward an alternative. For example, it has lambasted HMRC job cuts as billions of pounds in taxes go uncollected, and suggested this money could be used to pay for vital public services.

An effective PCS voice is all the more needed when Labour has signed up to what Serwotka has labelled "austerity-lite". It is primarily this that explains why Labour has not leapt to the defence of the PCS when under attack.

As we approach the crucial General Election in May, we can expect the tempo of political attacks on unions to increase. For the Tories, the best stick with which to beat Labour is that of the "union bogeyman", even though Miliband has reduced union influence inside Labour still further. It will then be hard going for PCS to fight back. But out of adversity, it may find strength in its own independently generated resistance.

Gregor Gall is professor of industrial relations at the University of Bradford and editor of the Scottish Left Review