Free kick and no card.
Referees are encouraged to correctly identify the difference between a challenge which stops a promising attack and a careless challenge. In this video, you can see the Haverfordwest attacker heading out towards the touchline in which he is carelessly tripped by the defender but is not in the process of a promising attack. It is also important to remember that the Barry Town United player is also on a yellow card and such major decisions as to send a player off from the field of play for a second cautionable offences should be a CLEAR cautionable offence.
It is also important that when carrying out the role of the assistant referee that you are aware of incidents particularly within your vicinity and that you can add value to a decision. Here the assistant referee utilising the communication headset that he is wearing, should have informed the referee that this is just a free kick and no further sanction is warranted.