Wren locomotives

Welcome!

I think the spellchecker has done for some of your content, and the question is 'are Wrenn locomotives compatible with Hornby Set Track?'.
The answer is that their OO product 'as originally supplied' by 'WRENN' and then 'Triang-WRENN' and then 'wrenn Railways' is compatible.
(See the useful 'History' section of this site: Wrenn Model Railways There's a whole lot more on that site which will be useful.)

Keep in mind that everything 'Wrenn' is now second hand, so past owners will often have altered their items, Rewheeling is quite common on locomotives, as the 'Romford' pattern wheels could be substituted for the typically off-scale originals, and all flanged driving wheel locos may be found: these will not work on Set Track. Look carefully at pictures and if the centre driver is not flangeless (or in the case of the 8F both second and third drivers flangeless) then don't purchase.

I have quite a few Wrenn locos (about 20) and they are tough and capable the wheels are quite broad and the flanges sharp and deep for which reason I chose Code 100 Peco which is settrack but the same as Streamline with a tighter base curves and of course tighter points, Going back along Wrenn track came out of Hornby Dublo and then whilst Horby was Triang it was Triang system 4 before becoming system 6 which was close to and morphed into the current Settrack system, you can also use Flieschman Profi and others such as Bachman equally as well. Wheel gaps are tighter - so no using the DCCConcepts gap gauge.

As to changes yes this may be an issue but really original Wrenn stock is very good and as someone who subscribes to the idea - if it is working don't fix it, so good stuff but not necessarily very accurate, Wrenn wagons are great too I have about 550 of them again because of the aluminium chassis/base they stay on the track but they do go off the rails in the 70's with a lot of strange private owners however the best option is original pre 1964 Hornby Dublo bodies on later Wrenn chassis, some of these mouldings are still made today as Wrenn passed through to Dapol along the way.

A pristine Bullied original Pacific is an expensive item although rarer is the unrebuilt Royal Scot and I do have one of those, the very common 8F has a too long wheelbase but 34c put a modern chassis under the body and it is really quite good.

So get it running and enjoy - so what have you got?