Chicken, Mayo & Anchovies

From Ben O'Donaghue. These are the flavors I love and I'd like to make this as soon as I can. He calls it poached chicken and tuna mayo salad, but it's basically a chicken tonnato. I've had veal and squid tonnato, so why not chicken too?

1 whole best quality chicken
2 spare ribs or pork bones
handful parsley stalks
4 shallots
3 cloves garlic
1 red chilli
1 tsp black peppercorn
maldon sea salt
500 gr new potatoes
8 anchovy fillets
2 tbls tiny capers
celery leaves
parsley leaves
tarragon vinegar

Tonnato
1 tin Italian tuna
3 egg yolks
1 lemon
500 ml EVOO
ground black pepper
maldon sea salt

1. wash & trim chicken of excess fat, place in pot; cover with cold water then add pork bones, parsley stalks, shallots, garlic, pricked chilli, salt and peppercorns
2. bring to simmer for five minutes, turn off
3. let stand one hour
4. remove chicken from pot and plunge into ice water to cool (reserve chicken stock for another dish)
5. make tonnato; make mayo first using eggs, EVOO and lemon; blend tuna and EVOO, fold in mayo
6. cook potatoes in salted water until tender, drain immediately and cut in half
7. dress with EVOO, splash of tarragon vinegar, add capers; keep salad warm
8. when salad ready to serve, toss the potatoes with parsley and celery leaves
9. to serve, pick the meat from the chicken, discarding the skin
10. arrange breast and thigh meat on a large white plate with the potato salad, dress with lashings of tuna mayo
11. garnish with anchovy fillets and more parsley and celery leaves