I had a chance conversation at Fianna Fáil’s presidential dinner in Dublin last Saturday night with a person who knows Mayo politics inside out.

We got to talking about the constituency changes there and the very real problem it has created for Mayo – and also indeed for Galway, but not Roscommon. If you were to put a name on it, it would be: ‘The John O’Mahony Conundrum’. A bit of background first before we get to the riddle.

Every time the Constituency Commission reports – by rights, soon after the latest Census has been officially published – there are always pockets of the country where you suspect the hatchet rather than the scalpel was wielded in the attempt to get an equal spread of representatives per population.

Before the 2007 General Election, Leitrim was hacked in two, with one half fired into Sligo, the other into Roscommon. For a while it was the only county in Ireland without a TD. The south and west of County Limerick suffered the same fate being shoved into North Kerry to allow the Kingdom retain two three-seat constituencies. Before that there was also the totally unsatisfactory amalgamation of Roscommon and Longford, divided as they were by province and by the River Shannon.

As Albert Reynolds’ right-hand-man Mickey Doherty once noted about transfers in the constituency: “Votes Don’t Swim”.

This time around the Commission had an unwinnable brief. The last census showed (surprisingly) that the population had increased, but yet it had to decrease the numbers of Dáil deputies (from 166 to 158). And that meant very hard decisions – and some big losers.

There have been some big gouges into county boundaries around the Border and Donegal, with real hybrid constituencies created. But it is around here that perhaps the most far-reaching changes have been made.

In the section on its report on the three western counties of Galway, Mayo and Roscommon, it states the population of the three counties is 445,000, which is equivalent to 15 seats.

Then comes the fateful paragraph: “An arrangement of constituencies based exclusively on country boundaries is not feasible. In particular, the population of Mayo can no longer form a five-seat constituency and Roscommon does not have sufficient population to stand alone as a constituency.”

And so we see the game of musical chairs start between the three counties with Mayo and Galway East both losing out, and Roscommon winning out. To reduce Mayo from a five-seat constituency to a four-seater meant moving a swathe of territory.

In the end, a total of nine electoral divisions around Ballinrobe with a total population of 10,300 – including The Neale, Cong, Shrule and Garrymore – have been moved into Galway West. Therefore Galway West stays a five-seater without having to steal any territory from Galway East. But there is no reprieve for the smaller constituency in Galway.

To retain its status as a constituency, Roscommon had to find a sizeable portion of another county to graft on to it, and sadly it was Galway East that took the hit. The constituency goes from four seats to three seats and has lost a whopping 32 electoral divisions and a population of 20,521.

It has meant that huge swathes of East and North East Galway from Ballinasloe through Ahascragh, to Glenamaddy, Creggs, Castleblakeney right up to the north of Dunmore have been lost. The Commission made the weak argument that nine electoral divisions in Galway East were once in Roscommon. But the others weren’t and while there is some contiguity along the border, the political and spiritual compass for all those places has always pointed to Galway.

For more, read this week's Connacht Tribune.