Surely there is hardly any weight above that door to need a lintel.
Although technically a lintel is the correct answer the door only needs to support about 10 bricks so its a bit of an overkill.
I bet if you take the trim off the top of the door you will find a gap between the frame and bricks of 10-20mm.
If so pack the bricks back up with some packers, foam up the gap, replace the trim and repoint.
<snipped>But Id bet a tenner on it that it would work.
Fordy could you answer a couple of questions for me please:
1. I assume this porch is quite old?
2. Did it originally have a wooden door that was replaced with the PVC door?
3. I assume that the PVC door is 2-5 years old, but definitely less than 10?
4. Was it fitted by a Fensa registered window company?
5. Is that company still trading and do you know who they are?
Depending on the answers to these questions you may be able to get the people who fitted the door to come back and sort this at their expense. If the answers are mainly or all yes I will post the relevant information to quote to them.
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