6-wheel coaches reduced to 4 wheels - when and why?

[Mol_PMB]

Ernie posted this photo recently showing a 4-wheel coach at Cork in 1955. It looks like a former GSWR 6-wheel 6-compartment third, but the middle wheelset has been removed and replaced with a truss to stiffen the underframe:

This intrigued me and I have gone down a rabbit-hole looking for more examples. Here are some other links which apparently show former GSWR 6-wheel carriages reduced to 4 wheels:

GSWR third at Glanmire Road, 1955 (possibly the same coach):

GSWR brake third 50 at Albert Quay, 1955: https://www.flickr.com/photos/irishrailwayarchive/53508677988

GSWR brake third 50 at Cobh Jct, undated: https://www.flickr.com/photos/irishrailwayarchive/53511332173

GSWR (ex-WLWR?) 5-compartment third 933 in 1948: https://www.flickr.com/photos/irishrailwayarchive/53508746396

GSWR 4-compartment third (ex-first?) 382 at Newbridge in 1948: https://www.flickr.com/photos/irishrailwayarchive/53508747351

 

So, what was this all about?

When were the vehicles modified and why? 

Some seem to have outlasted similar unmodified 6-wheelers.

Any more info would be welcome and may result in a model.

 

[Colonel]

Some forward thinking dude was making them easier to model?

[Mol_PMB]

There's an old thread on 4-wheel coaches in Ireland here:

https://irishrailwaymodeller.com/topic/12485-two-axel-coaches-in-ireland/

It has plenty of useful info on early 4-wheelers but I can't see anything specifically about these conversions of GSWR 6-wheelers.

The brake third number 50 wasn't withdrawn until 1959, and the 6-compartment third in Ernie's photos was apparently still in traffic in 1955. These 4-wheel conversions must have been some of the last GSWR 30' coaches of their type in traffic. 

I wonder if they were converted for use on routes where 6-wheelers were prohibited?

 

[cheesy_peas]

At a guess I'd say it was for the odd excursion to Courtmac or Macroom where lots of things were prohibited from travelling over and the native coaching stock was life expired. Make do and mend stuff.

Edited Friday at 10:46 by cheesy_peas

[Mol_PMB]

I bought a few old Irish prints on ebay recently and here's one that belongs in this thread:

The photo is dated 1953 and the location is Inchicore. The handwritten caption says it is number 89 but looking closely at the print I think I'd vote for 88.