How deep does the pipe from the meter to the house inlet need to be

The previous posters answer is wrong, his measurement vaguely relates to the buried depth of the gas service not from above ground level height. As long as there is sufficient clearance from the ground surface level to the gas service pipe and it is properly bracketed to prevent movement also the pipe must not come in direct contact with the masonry surface especially if it is of a brick construction then all is in order (air gap between pipe fixing surface) I normally install it above the damp proof course, note also the new gas service pipework MUST be of sufficient size to transport enough volume of gas to serve all fixed appliances which your installer should of factored in before the installation was undertaken. Also note that when I install a new gas service around the perimeter of a property I have to take into account if there are areas of the pipe run that maybe prone to accidental damage so therefore we take additional measures to protect the gas service from this.

It doesn't need to be below the ground at all. It can run alongside house but if it is underground on a residential property I believe it needs to be atleast 325mm. If its showing like you say, that is not safe and you need to get it inspected.