Many thanks, I bought this book about an hour after you mentioned it and had a look at it. Not surprisingly it doesn't seem to contain any truly new knowledge which isn't already on this forum. Moreover it is not really BIR-style since it doesn't use neither a base gravy/Garabi nor a restaurant masala/spice mix.
However, at the price you really can't go wrong. I found it to be quite interesting and the recipes appear to make sense even if not true BIR-style. Their advantage is that they require relatively few ingredients. The book is 187 pages so you get a lot of value for your (very little) money plus you help someone with a pretty devastating illness (Social Anxiety Disorder) earn a living. I actually enjoyed all the non-recipe content the most (Basics, Info about Ingredients ("Spiceopedia"), Methods, Shopping List, Curry Heat League Table, How to Impress Friends).
Here's one of the recipes so you can get a feel what the book is like:
TANDOORI CHICKENA most popular starter with its lightly spiced bright red chicken pieces blended with yoghurt. Marinating helps to make the chicken succulent. Serve with a green salad.
Spices
1/2 teaspoon ginger
1/2 teaspoon garlic
1 teaspoon garam masala
1/2 teaspoon chilli powder
Other ingredients
1 dessertspoon natural yoghurt
2 dessertspoons of cooking oil
A dash of lemon juice
1/2 teaspoon salt
1 dessertspoon tomato ketchup
A drop of red food colouring (if you want to create the restaurant look)
2 breasts of chicken left whole or sliced into thick strips.
1. Put all of the spices into a cup and add a little water. Then mix into a paste.
2. Add two dessertspoons of oil into a pan and place onto a high heat.
3. Add the spice mixture and stir constantly for five minutes. Reduce the heat setting if the spices stick and add a little warm water from the kettle to avoid burning.
4. Drain off the oil and allow the spice mixture to cool.
5. Add the spices, salt, lemon juice, ketchup, food colouring and yoghurt into a mixing bowl and blend to a creamy paste.
6. Add the chicken to the spice mixture and blend the mixture together.
7. Prick the chicken with a fork to allow the marinade to seep into the meat.
8. Allow for marinating in the refrigerator for at least two hours.
9. Place the coated chicken pieces onto a foil lined grill pan and grill for twenty minutes on a high heat turning occasionally.
10. Transfer to serving dish and serve with fresh salad.
While I was at Amazon I also bought another book I found there while browsing:
Kenny McGovern - The Takeaway SecretThis one follows the base gravy/spice mix method as BIRs. Again, not really any new knowledge which is not on here somewhere but I really do like this book for some reason.
There's also a specialized edition "
The Indian Takeaway Secret" available by the same author but the same content is included in the "full" version, too, so I recommend getting the full one instead because the extra stuff is quite interesting to me at least (Indian & Turkish Kebabs, chip shop recipes, chinese TA recipes, Pizza stuff, sides/salads/sauces as well as drinks & desserts). It makes for a nice change

Here's the Base Gravy recipe from that book:
BASIC CURRY SAUCE(INDIAN RESTAURANT STYLE)
Makes enough Basic Curry Sauce for 7?8 Curries
This curry sauce can be frozen in batches and used in a diverse range of finished curry dishes. With the basic curry sauce prepared and ready for use, any of the curry dishes in this chapter can be created in around 10 minutes.
75 ml (2 1/2 fl oz) vegetable oil
2 carrots, chopped
1 1/2 large Spanish onions (around 700 g or 1 1/2 lb peeled weight), chopped
1/2 green pepper, chopped
2 1/2 litres (4 1/2 pints water)
2 tablespoons tomato pur?e
1 tablespoon garlic and ginger paste
1 teaspoon coriander powder
1 teaspoon cumin powder
1 teaspoon turmeric powder
1/2 tablespoon garam masala
1 large handful of chopped fresh coriander leaves and stalks
200 g tinned chopped tomatoes
25 g (1 oz) creamed coconut block
1/4 teaspoon salt
Heat the oil in a large stock pot and add the vegetables. Stir-fry over a medium heat for 5?6 minutes.
Add the water, tomato pur?e, garlic and ginger paste, coriander powder, cumin powder, turmeric, garam masala, fresh coriander, tinned tomatoes, creamed coconut block and salt.
Bring the pan back to the boil on a high heat. Once boiling, reduce the heat to medium-low. Simmer for 1 hour.
Using a hand blender, blitz the sauce. Continue blending for 2?3 minutes until no vegetable pieces remain and the sauce is completely smooth.
Return the pan to the heat and simmer for a further 15 minutes. Add a little more water if necessary. The finished sauce should have the consistency of a thin soup.
Allow the sauce to cool and pour into freezer safe storage tubs. Freeze in 200?300ml/7?10 fl oz batches for up to 3 months. Each batch will provide enough basic curry sauce for 1 portion of curry.