The draw was a good outcome for the Bluebirds, who are seven points in front of the second-placed Martyrs and now third-placed Canaries who, however, possess a couple of games in hand on the top two.
They fell behind after 13 minutes when recent signing Jack Compton put Merthyr in front. Liam Brooks equalised 11 minutes later and then Danny Webb put Hitchin ahead after 58 minutes.
It didn`t look good for the hosts, or the majority in the 535 crowd, when Scott Barrow was shown a straight red card following after a tackle in midfield but five minutes from time, the ten-men grabbed a leveller through Corey Jenkins.
There was a shock for fifth-placed Slough Town as they became bottom side Cinderford Town`s third successive victims.
The Foresters looked dead and buried until two wins lifted them to within sight of second-bottom Hayes & Yeading United. And now that gap is seven points after Craig Norman`s 43rd minute opener for the hosts was added to by Elliot Ford on 64 minutes – 11 minutes after Nathan Smart had pulled the visitors level.
Kettering Town moved level on points with sixth-placed Banbury United, but are still nine behind Slough, after a best-of-five win at Creasey Park against Dunstable Town.
Aaron O`Connor put the Poppies in front after 23 minutes but went into the break all-square after David Longe-King and Vences Bola had levelled O`Connor`s second for the visitors. Rene Howe then won it for the Poppies with 12 minutes remaining.
Elsewhere, Chesham United halted a run of four successive defeats with a 2-0 win at the ProKit Stadium against St Ives Town with second half goals from Ryan Blake after 64 minutes and Sam Youngs 11 minutes from time.
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